Inlet manifold spacer 13122-37990

[allen]

Hi my bike does not have the spacer 13122-37990 between the inlet manifold and the proper unit, it has the one between the carburetor and the manifold. How important is the spacer at the proper unit, I am still chasing some carburetion gremlins that come in when the engine is very hot, that are not there when the engine is just up to operating temperature.

Regards Allen

[FC Zach]

Regarding the issue when hot, does it run without using choke?

[allen]

Yes runs without choke, just becomes erratic as you crack the throttle and appears to lean out.

[steve w]

HI THE SPACER BETWEEN THE PROPER UNIT AND INLET MANIFOLD WAS A MODIFICATION TO STOP THE HEAT TRANSFERING AND BOILING THE FUEL AND COULD WELL BE CAUSING YOUR PROBLEM. HOPE THIS IS SOME HELP.


STEVE

[wayne]

There are two spacers as you rightly say. I believe that the if the bike is fitted only with the carby/inlet spacer, then this was most likely done at the dealership. As a retrofit for bikes already sold, the dealers were only supplied with the bits to do just the one insulator.

If your bike has both then either a diligent owner at some point has fitted it or perhaps the factory started fitting them on the later production line bikes.

I think the second insulator at the engine/inlet is worth putting it. It seemed to help my bike's hot running. I do know that the hot running difference between my bike now compared to when I first got it recommissioned is significant. I think it's more than just the insulator, but it sure isn't going to hurt.

EDIT: when I say it helps the bike's hot running, I'm referring to sitting in bumper to bumper traffic on a 40 degree C day. Any issues you have testing in the garage won't, as Zach notes below, be fixed by the second insulator.

[allen]

Hi Wayne, since carburetor cleaning and refitting it to the bike, I run the bike each day in the shed as it is not rideable yet, only when I let it get hot hot it develops what I think are carburation issues, so I would like to fit the other spacer at the proper unit.
If I cannot find one at a reasonable price I will manufacture one and try that.

Thanks for your input, Regards Allen

[FC Zach]

Like others have said, installing the spacer definitely won't hurt but I highly doubt it's going to fix your issue. Is this at idle only? It could be as simple as an adjustment being out. Have you adjusted the idle mixture, float level, etc. . .

What's the compression? Where is the needle on the temp gauge when this happens?

[allen]

Carby ultrasonic cleaned, float level checked, new diaghprams and gaskets, new needle and seat, carby angles set and cables adjusted, port valve timing checked, pilot screw adjusted, carby and manifold checked for air leaks, engine timing set to 5 deg, and other settings tried. Spark plug adaptor and new spark plug fitted, fresh plug tried.
no compression test, only by what is evident at the kick starter and I believe its good. No temp guage connected as yet.
Engine starts easily and idles well, revs good with slight flat spot on transition to secondary.
Once the engine is hot after being run on and off for a while it appears to start to lean out and play up, let it cool a bit and it ok.
I will carry out some more tests on the weekend in relation to heat and fuel and see what I get.
I will introduce extra fuel into the secondary port when it is playing up and see if that affects it.

Regards Allen

[FC Zach]

Dec 16, 2015 6:32:52 GMT -5 allen said:

Carby ultrasonic cleaned

This is good but never assume it's done and ready for use just because it has been ultrasonically cleaned, sometimes I've had to clean them two or even three times for positive results.

Dec 16, 2015 6:32:52 GMT -5 allen said:

no compression test, only by what is evident at the kick starter and I believe its good.

The feel from the kick starter means nothing, these bikes are inherently difficult to start/rotate with the kick starter.

Dec 16, 2015 6:32:52 GMT -5 allen said:

No temp guage connected as yet.

I'm curious how hot it's getting when this is happening, get a gauge hooked up and post some results.

Dec 16, 2015 6:32:52 GMT -5 allen said:

Engine starts easily and idles well, revs good with slight flat spot on transition to secondary. Once the engine is hot after being run on and off for a while it appears to start to lean out and play up, let it cool a bit and it ok.

Whenever you can get a compression tester (conventional is fine) hooked it up, share the results. It's very possible that you are losing compression once warm. The little hiccup during the transition into the secondaries is 'normal'

Two other very important things to check if you haven't already. .
1. OMP check valve to the carb bowl, make sure it's functioning properly
2. Ensure that the OMP is pumping oil. Sometimes the tank/line get clogged and cause weak or zero flow.

[FC Zach]

Dec 14, 2015 13:48:07 GMT -5 allen said:

Yes runs without choke, just becomes erratic as you crack the throttle and appears to lean out.

Re-reading your posts, I missed this one. . I'd recommend pulling the carb back off and cleaning it in the ultrasonic again as well as shooting carb cleaner and compressed air through all the passages. I worked on another members bike earlier this year that had a very similar issue like yours. This is of course after rechecking and triple checking everything. And you are sure it's nothing else but the carb.

[steve w]

hi if I recall you will need longer studs to allow for the spacer thickness.



steve w

[jm0406]

I have been reading this post as it goes along, could it be something as simple as fuel flow from the tank through the petcock? Restricted fuel flow would give you the same lean condition you are seeing, and when it sits a bit, fuel fill the bowl again.

Jeff

[timpa136]

Good points Zach, Steve and Wayne and Jeff.

Rotorious fixed a friends Carb with the vent plugged in the bowl doing just as Jeff describes but it hadn't been cleaned like Allens.

The spacer will fit without longer studs on the engine.

Before you fit the spacer, clean and seal the intake manifold and powder coat if possible. Many manifolds are porous both to the outside and between tracks internally, better suited to aquarium oxygenators in your man cave.

I have a NOS spacer as fitted on all the A models for sale please PM me if interested.

Zack made an important point, is the bike overheating from a clogged radiator? You don't want to start peeling side coatings from overheating.

edit, Wayne said EDIT: when I say it helps the bike's hot running, I'm referring to sitting in bumper to bumper traffic on a 40 degree C day. Any issues you have testing in the garage won't, as Zach notes below, be fixed by the second insulator.

I was going to add, I run a fan in the garage into the radiator, too when extended running.




Tim