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1Back to top Go down    K75RT Fuel Cooler on Thu Mar 19, 2015 10:30 pm

Point-Seven-five

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Starting a new thread to document the installation of a fuel cooler on my '94 K75RT.

Picked up this cooler on eBay. Looks pretty nice and has as many fins internally as you see on the outside. Has a pretty good volume that should give me about 40 seconds of residence time. Extruded aluminum body looks pretty snazzy and doesn't require any protection from stones and other debris.



Got it here: http://www.ebay.com/itm/10-Silver-Anodized-Dual-Pass-Transmission-Oil-Cooler-With-Fittings-/201154322208?pt=Motors_Car_Truck_Parts_Accessories&hash=item2ed5bb5f20&vxp=mtr

5/16" hose barbs: http://www.ebay.com/itm/331396623114?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I am mounting the cooler horizontally below the radiator and in front of the cam chain cover. Hose connections will be on the left hand side. The mounting bracket will be bolted to the lower radiator bracket. I removed the existing flat head screws and the body nuts they screwed into. Replaced them with 25mm long 6mm bolts with fender washers, lock washers and nuts. The bracket goes in under the mounting tabs for the fan. Bolts go from the inside with the nuts outside.



Bracket is approximately 3mm thick stainless steel. Drawing with dimensions I used to follow.


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

2Back to top Go down    Re: K75RT Fuel Cooler on Thu Mar 19, 2015 11:29 pm

Point-Seven-five

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Cooler Mounting Bracket. Note: I am not a draftsman...


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

3Back to top Go down    Re: K75RT Fuel Cooler on Thu Mar 19, 2015 11:59 pm

BadjerJim

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Awesome! Thanks!

    

4Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 20, 2015 12:39 am

RicK G

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This is the cooler on Charlie99s bike. Mine on the K1100 is the same and attached directly to the grill of the fairing

it works so well that on a cold morning I don't get the nice warm tank to keep the knees warm.


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

5Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 20, 2015 3:31 am

charlie99

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can I add something to the thread ?

if you decide to place it low across the timing cover consider this ....rocks, chips of stone, sand etc bombard the timing cover from the front wheel flyup on a standard setup

if you extend the front fender (on the rear ) by about 75-100 mm... you might find that the spray pattern of chips and debris doesn't get as high on the front covers ...maybe only as high as the oil pump

has made a huge difference for me ......just a thought ( I could have some before and afters pics if your interested )

ps .

..don't forget to protect the feed and outlet lines from debris exposure ...the refrigerant insulation tubingdoes a fairly good job at this ...it will not protect during a crash event at all ...be aware !!


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

6Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 20, 2015 9:07 am

Point-Seven-five

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Good observations, Charlie. I have just taken delivery of an Extenda Fenda to do exactly what you suggested. As far as fuel line exposure, With any luck they will be mostly behind the radiator fairing.

I have positioned the cooler as far over to the right of the bike as possible limited only by the cooling hose that is on that side in front of the crankcase cover. I don't think stones will be much of an issue on the fuel lines as witnessed by the aforementioned coolant hose.

I am also planning on shortening the hose barbs and have chased the 1/4" NPT threads in the cooler to get the ends of the barbs in toward the centerline of the bike as much as possible. I've gotten about 3/4 to 1".

Will be heading out to the garage in a little while when things warm up a bit more. Need to run into town this morning to get another drill bit as the darn stainless I am using is a welding grade and merciless to cutting tools.


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

7Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 20, 2015 9:19 am

Point-Seven-five

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Rick, I looked at your installation originally, but couldn't figure out a way to mount the cooler without getting rid of the radiator fairing. Thought about going below the radiator fairing, but couldn't think of a way to neatly protect the fins with the limited fabrication capabilities at hand.

As you can see, the cooler I have settled on is a fairly robust if somewhat bulky unit that I expect will keep things close to ambient on the hottest days at the slowest speeds. The only thing I give away to Charlie's design is that I do not have the benefit of the fan drawing air over my cooler when at a standstill in traffic. Still, I think the open design of the cooler, and it's being unenclosed will allow a fair bit of convection air flow round it. That with the extended residence time should keep the exit temperature reasonable even at a standstill.


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

8Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 20, 2015 3:31 pm

Point-Seven-five

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Cooler is mounted. Revised bracket above will get about 1/4" more clearance to the bottom of the radiator fairing.

Need to cut down the hose barbs and get a chunk of fuel line to finish things up. At least I know the cooler fits and doesn't stick out too much.





One ride this year and already the bike is filthy! Still too cold to wash her.


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

9Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 20, 2015 3:48 pm

Kyle10

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Now that looks good.


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1985 K100rt 0052183
1983 Honda VF750 007713
    

10Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 20, 2015 4:52 pm

Point-Seven-five

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Plumbed.





Going to put a little insulation on the exposed hose. Need to touch up the Left side lower before I put it back on.

I think it looks pretty good. Radiator grille hides it pretty well. Hoses look to be out of the way.


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

11Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 20, 2015 6:21 pm

robmack

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I like the looks of that cooler. It's prettier than run of the mill coolers with plate metal fins.

Couple of questions.

How will you be comparing the before-install and after-install temperatures of the fuel?

Would it be an idea to include a bypass valve in case the hoses or cooler springs a leak?


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

12Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 20, 2015 6:42 pm

Point-Seven-five

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Thanks Rob, before/after comparison will be this summer, probably as soon as early May when I can run a full tank of gas down to about a third of a tank and not have my thighs barbequed.

Don't know about a bypass valve; sounds like extra plumbing, fittings and chances for leaks. There is not that much additional hose in the circuit. I only added one hose about 15" long running from the cooler back up to the tank. The cooler itself is probably the most bulletproof part of the fuel system. The body is an aluminum extrusion, and the 3/8" thick end caps are nicely welded on. I may add quick disconnects in the lines, just to make removing the cooler or tank easier.


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

13Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 20, 2015 8:56 pm

BadjerJim

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Great work. Thanks for the pics and the details.

    

14Back to top Go down    Re: K75RT Fuel Cooler on Sat Mar 21, 2015 12:30 pm

k-rider

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That looks really COOL 😎

Good work .
If you should be so unlucky to have a leak at the cooler ,,just carry a short piece of 8mm. Pipe
Use it to connect the hoses instead of the cooler .

K-rider


15Back to top Go down    Re: K75RT Fuel Cooler on Sat Mar 21, 2015 1:29 pm

Point-Seven-five

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Thanks for the kind comments.

I don't think that this cooler is going to leak. It is a fairly heavy wall extrusion. Much stronger than the conventional coolers that are built like radiators. Being afraid of a fuel leak was the main reason for selecting this particular cooler, I wouldn't want to risk the other type of cooler. Not only are the cooler walls heavy, but the welded end caps are about 10mm thick. If there are going to be any leaks, they would be in the hoses, and they would be there even if the cooler wasn't.

The hoses connecting the cooler are really tucked away well behind the radiator and the left side lower fairings. The only exposure is about 4-5cm right at the cooler connections. There is actually less exposure than the standard fuel lines on a naked bike. I could get better photos of the installation, but the bike is wedged into a small corner of my garage right now in a position that makes getting a good picture impossible.

Bottom line, except for adding about 35cm of hose and two clamps, there isn't anything that would make the fuel system less reliable. And remember, this is in the return line where the pressure is only high enough to push the fuel back up to the tank at a head of about 50cm at the very most.


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

16Back to top Go down    Re: K75RT Fuel Cooler on Sat Mar 21, 2015 3:51 pm

BadjerJim

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And what's really beautiful about this mod is... That if it doesn't work out for any reason you can put the bike back to stock in a few minutes.

I agree with the above comments, I was afraid of pushing GASOLINE through a thin-walled conventional radiator, for fear that the smallest rock chip would make a leak. I've got this cooler in hand right now and it is very beefy, made of strong extruded aluminum. I would have expected it to cost $100 at least.

At $25 it's a real bargain. Can't wait to get it hooked up.

    

17Back to top Go down    Re: K75RT Fuel Cooler on Sat Mar 21, 2015 5:00 pm

Crazy Frog

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Thanks for all the info Point-seven-five.

I am still waiting for mine to arrive.

I don't have any idea when I will be able to test it, but here in Eastern Canada, we are working really hard to get rid off the winter and start our biking season.



I know it's been a rough winter because my snowblower has more kms on it than my motorcycles.


__________________________________________________
1986 k75, 1985 K100rt, 1985 K100rt/EML sidecar.
    

18Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 27, 2015 6:57 am

Crazy Frog

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me thinking.....

As I have multiple options to install the unit, I am wondering what would be the best position.
Should it be mounted facing the road(#1) or parallel to the frame of the bike(#2)?
What do you think is the most efficient?


__________________________________________________
1986 k75, 1985 K100rt, 1985 K100rt/EML sidecar.
    

19Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 27, 2015 7:24 am

92KK 84WW Olaf

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I took out my thermal lining last weekend.

I must try some bbq snowman too. Last one I tried was a peaty taste and kind of interfered with my head. Must have been the Scottish snow.

Fuel cooler looks excellent and have seen those type. They are quite robust and should do well. The extended front fender is essential as the efficiency of the cooler is reduced if its caked up.

I have noticed when the gas tank is full the fuel stays cool but whenthe levelgets low it gets very warm.


__________________________________________________
1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 58,645 now 60,500miles
    

20Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 27, 2015 7:27 am

indian036

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If I had the flexibility in positioning, I'd be using position 2. When mine arrives, I'll be using version 1 as Point-seven-five has done, but I don't think the difference either way will be massive.

Bill


__________________________________________________
1985 K100RT Red. VIN 0028991K100RT ENG 104EA248523386
1985 K100RT Blue. VIN 0029036K100RT ENG 104EA25852071
1990 K100LT Black. VIN WB105060310190452
1984 K100RT White. VIN. 0023022K100RT ENG 104EA32848523
    

21Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 27, 2015 7:50 am

K75cster

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I'd believe option 1 with airflow over the greater area as it appears the unit is infact a u shaped tube with entry and exit at the same end this gives the air greater impact on the unit especially if the u is upper and lower meaning air cools the whole length at point of impact then the heat escapes taking the heat with it the back side without direct air is still large enough to assist with cooling


__________________________________________________
Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

22Back to top Go down    Re: K75RT Fuel Cooler on Fri Mar 27, 2015 11:03 am

Point-Seven-five

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Option #2 is the most efficient, but difficult to implement on my RT. Bert's bike with the chair should be able to go this route without much trouble.

Option #1 does have the benefit of more turbulence around the fins although the back side won't see as much airflow. Because it is a two pass cooler with the passages horizontal in my installation, it is best to have the entering fuel at the backside where the airflow is less and the cooler body is not as cool as the front. This is to maximize the temperature difference between the fuel and the cooler body and thus the heat transfer.

One of the features of this cooler that I liked was that it has an internal volume greater than 1/2 liter which should give the fuel something like 40 seconds of residence time in the cooler as it passes through. That will allow lots of time for heat transfer as opposed to the radiator type coolers that hold a lot less.

My cooler is installed, and as soon as the weather breaks I hope to get out for a trial run. Later in April I am hoping to make a trip to Colorado, about 3500 miles round trip. I will be reporting on how it works after the trip.

Olaf, low tanks are probably getting warm because there is less fuel to absorb the heat. With 1/2 the mass, the same heat input will raise the temperature twice as much. A low fuel level also has less contact with the walls of the tank and the walls it is contacting are at the bottom where the insulation is installed. The fairings don't help with cooling the tank either.

This cooler really looks good on the bike, what you can see of it since being below the radiator shroud it is invisible when you are within 5-6 feet of the bike, and even at a distance it blends into the front of the engine. You have to be looking for it to even notice it. My engine is all black with the silver cooler. Would have been nice to have the cooler in a black anodize. Maybe next winter...


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

23Back to top Go down    Re: K75RT Fuel Cooler on Wed Apr 22, 2015 5:27 pm

Crazy Frog

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As I am a cheap guy, I always look for bargains.
Here is a very efficient type of cooler not costing an arm and a leg Very Happy.
In fact it could act as a gas tank.


__________________________________________________
1986 k75, 1985 K100rt, 1985 K100rt/EML sidecar.
    

24Back to top Go down    Re: K75RT Fuel Cooler on Wed Apr 22, 2015 10:54 pm

Point-Seven-five

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Holy Crap! Where do you find those pictures?

Update: Just finished the second day of a three day run to Colorado. 540 miles yesterday, and 660 today. Ambient temperatures in the 50-60 F range. No perceptible rise in tank temperature above ambient both days. No operating issues or leaks to report with the cooler.

Looks like a winner.


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

25Back to top Go down    Re: K75RT Fuel Cooler on Sat Nov 19, 2016 2:42 pm

Point-Seven-five

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Just coming back to report on two seasons and nearly 20,000 miles on the cooler including a week of riding in New Mexico, Utah and Arizona in temperatures up to 118F/45C.

The cooler has been totally trouble free, in fact, I have just about forgotten it's even there. The best part is that "hot tank syndrome" has been eliminated, even in last summer's desert heat. I still get some heat coming up from under the fairing, but it isn't as bad as what I was getting from the hot fuel in the tank.

The bike is way more pleasant to ride now.


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

26Back to top Go down    Re: K75RT Fuel Cooler on Sat Nov 19, 2016 9:19 pm

charlie99

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good to hear someone else has done the mod and experienced the effect

ride well


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

27Back to top Go down    Re: K75RT Fuel Cooler on Sat Nov 19, 2016 9:37 pm

indian036

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I finished up deciding to use a standard transmission oil cooler type, mounted to the front of the radiator screen. Cheated by using cable ties, but it hasn't moved.

Its been very successful, going from not being able to grip the tank with my knees on anything other than a cool day, to no problem even on the hottest days.



My recent run to Guyra and smithy's place on BOB the Blue Old Bike showed a slight tendency to be warm, even though the weather on the whole was pretty pleasant. Nothing like the red bike, but to be sure, I've sourced a fairly similar cooler to be installed on it, one of these days.

Bill


__________________________________________________
1985 K100RT Red. VIN 0028991K100RT ENG 104EA248523386
1985 K100RT Blue. VIN 0029036K100RT ENG 104EA25852071
1990 K100LT Black. VIN WB105060310190452
1984 K100RT White. VIN. 0023022K100RT ENG 104EA32848523
    

28Back to top Go down    Re: K75RT Fuel Cooler on Sun Nov 20, 2016 7:37 am

Dai

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Oh well, at least they're black cable ties.


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

29Back to top Go down    Re: K75RT Fuel Cooler on Sun Nov 20, 2016 7:53 am

indian036

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@Dai wrote:Oh well, at least they're black cable ties.
I couldn't have borne the shame of white ones! Wink

Bill


__________________________________________________
1985 K100RT Red. VIN 0028991K100RT ENG 104EA248523386
1985 K100RT Blue. VIN 0029036K100RT ENG 104EA25852071
1990 K100LT Black. VIN WB105060310190452
1984 K100RT White. VIN. 0023022K100RT ENG 104EA32848523
    

30Back to top Go down    Re: K75RT Fuel Cooler on Sun Nov 20, 2016 4:54 pm

K75cster

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What is that cooler off Bill?


__________________________________________________
Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

31Back to top Go down    Re: K75RT Fuel Cooler on Sun Nov 20, 2016 5:06 pm

92KK 84WW Olaf

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For 9 months of the year here the warm fuel is quite welcome, especially just now while we are zero temperatures.

But in France last year when we had 35c hot fuel was bad. So this idea is very welcome and seems quite easy to fit too.


__________________________________________________
1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 58,645 now 60,500miles
    

32Back to top Go down    Re: K75RT Fuel Cooler on Sun Nov 20, 2016 6:18 pm

indian036

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@K75cster wrote:What is that cooler off Bill?
It's a generic found by doing a search for "transmission oil cooler" on eBay. No idea what it is designed to fit, but I just checked published dimensions for the space where I fitted it.

The one I have for BOB the Blue Old Bike is slightly different in dimensions, and is even pre-painted blue, though lighter than the bike's blue.

I did have to do some searching for the fittings for the fuel hose to cooler interfaces.

Bill

PS. Make sure it's installed on the return line so it's not under fuel pump pressure.


__________________________________________________
1985 K100RT Red. VIN 0028991K100RT ENG 104EA248523386
1985 K100RT Blue. VIN 0029036K100RT ENG 104EA25852071
1990 K100LT Black. VIN WB105060310190452
1984 K100RT White. VIN. 0023022K100RT ENG 104EA32848523
    

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