Board index Flathead Power-Technical Questions, Answers, and Suggestions 45 Flatties M88 advise

M88 advise

Moderators: Curt!, Pa

Post Mon Oct 22, 2012 6:00 am

Posts: 186
I have this M88 I want to use on a WLA without oil bath air cleaner.
I dont have the Linkert knowledge, to work out if the fixed jet #1, and the body plug are installed in the correct locations on the bowl stem.
Obviously I have the fixed high speed needle, on the LHS, and the adjustable low speed on the other side.
Thanks very much in advance. Great website.
Cheers Keith
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Post Mon Oct 22, 2012 7:23 am

Posts: 3011
Location: Central Illinois, USA

Since both passages enter the same chamber, the positions are of no consequence to the performace of the carburetor.


Post Mon Oct 22, 2012 8:02 am

Posts: 186
So if I swapped them around, or even plugged both holes, the carb should work??
Thanks keith

Post Mon Oct 22, 2012 9:04 am
Pa Site Admin

Posts: 5552
Location: Ohio USA

I agree with Cotten but the jet was normally installed in the rear port acording to early service manuals. You do need the jet or they would not have installed one. I am not sure why it is needed since the high speed needle seats all the way in and is locked down.

Post Mon Oct 22, 2012 7:57 pm

Posts: 186
Thanks for the advise. I will leave it like it is then, and see if it works.

Post Mon Oct 22, 2012 8:21 pm

Posts: 386
On a standard SV carb the fuel is metered by the needle. When H-D supplied the military models the decision was made to use a fixed jet and seat the needle all the way in to be able to remove the adjustment capability from the rider. If you want an adjustable feed you merely need to swap the fixed jet for a plug and replace the seated needle and lock plug with a standard M-51 needle. But if you use the standard M-88 needle and lock plug you must have the fixed jet, whose size was determined as the best overall in most conditions!

Post Mon Oct 22, 2012 10:06 pm

Posts: 186
Very good explanation. Thanks very much.

Post Mon Oct 22, 2012 10:57 pm
Pa Site Admin

Posts: 5552
Location: Ohio USA

Thanks Robbie ! Now I know why the needle is seated fixed. The metering is calculated at best performance standard for guys like me. LOL...All kidding aside, the fixed jet and needle metering is a no brainer when one thinks of the reasoning behind it.

Post Tue Oct 23, 2012 7:48 am

Posts: 3011
Location: Central Illinois, USA
Just wondering, Folks,

How do we know if the standard fixed jet will be proper tune for a machine with some overbores, on modern fuels?
Does removing the oilbath call for an adjustment?

Thanks in advance,


Post Tue Oct 23, 2012 9:01 am
Pa Site Admin

Posts: 5552
Location: Ohio USA

I think any drastic changes in bore size and fuel would affect performance but to what extend is the real question. Would such drastic changes require adjustable high speed settings ?

Post Tue Oct 23, 2012 7:41 pm

Posts: 186
I have a bone stock 45 (WLA) that I ride nearly everyday.
I don't use an oil bath aircleaner, only a air snoot.
The carb is M88, same as in my pictures above. Not sure if I have the fixed jet#1 on the RHS port, and the plug on the LHS.
I don't want to take the bowl off, to look.
Pretty sure it has a brass float as well.
Has the fixed high speed needle with plug
The low speed needle is out 2 3/4 turns.
Bike runs perfect, always has since being restored. I wish my other 45 was the same.
May-be this will help someone.
Thanks Keith
ps Tried to updoad a picture, but file too large.

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