Quote:
Originally Posted by Bob KellyIII
What is it .... #4 copper washers used for shims ????
you should pick up at least 4 of those too while your at it as you may need them. or just run to the hardware store for those...
I really didn't notice any difference in the running due to the Main jets just a tiny bit leaner... from 98's down to 95's is a very small change... I expect to see a change in plug color, but it won't be much... I really think the big change came from the shims.
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when I was porting and polishing 2 strokes in my younger years it was not uncommon to go 3 to 4 sizes due to all the material I removed from the ports
and the engines were like a completely different animal ! though the big changes were adding tuned pipes ! that really changed the machine ! 
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Bob.... |
Quote:
Originally Posted by Bob KellyIII
I don't usually change pilot jets ever....unless the fuel/airscrew makes no change at all
which is usually not the case even with changing the main jet.....
however I have noticed that unlike the first adjustment I did to the bike that now for some reason the fuel/air screws don't seem to change anything as far as the idle goes which is very weird.... I suppose that the carbs could have been so dirty in the last year or so that they were dirty enough to actually be just right... LOL and now that their clean the hole is too big ! HAHAHAH
so I may also have to reduce the size of the pilot jet as well.
but I do have the fuel/air screws out a long way... 3 to 3.5 turns out but they did NOT change the RPM of the engine at all ...unlike the first time I got it running good I could easily tell the change in the RPM of the engine idling even without killing one cylinder
this time the fuel/air screws had no effect what so ever.....
Maybe that is a hint to the problem ? it only started running half way decent when I put the screws out to 3 turns out at 2 turns the flat spot was so big I couldn't get over it at all.... it started having a flat spot at 4,000 RPM and would not take any more throttle for love nor money ! once I opened the airscrews to 3~3.5 then I could get over the flat spot at 6,000 RPM and it ran ok from there to red line sense I got the carbs back from Gordon they were alot better but only after I opened up the fuel air screws.
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but Jets shouldn't change in a years time (asuming they arn't all gunked up and dirty)
so what could change the first tuning I gave it where the fuel air screws adjusted it perfectly.... to now ?... the main jet does not effect that circuit but it is not isolated from it
and it's my belief that the carb is designed so lean that it needs the pilot jets to be perfect in order to run top notch because they dump fuel into the airstream all the time
and they plan on that in the design of the carb..... adjust the fuel air screws too lean and the bike will fall on it's face trying to take throttle just off idle that is normal but even more so with these carbs it will carry on to mid range not just off idle....that is probably WHY the flat spot at 4~6k RPM the answer would be to dump in more fuel than usual into the air stream as soon as the throttle opens, hence the shims.
and it seems to have worked for the most part...because when the engine is good and warm (at operating temperature) it runs great ! it just takes 10 minutes to get that thing warm !
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Bob.......
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Thanks Bob, I'm hopeful but not expecting a drastic change with the replacement jets given the severity of the rich running condition but it will be a good starting point to continue testing and reading the plugs until its running correctly.
As suggested, I will plan to acquire some #4 shims for experimenting. This article suggests you are correct on the shim size:
https://faq.ninja250.org/wiki/Washers_for_carb_needles