Jetting 84 250r

[ivan-083]

Hey guys
I've got my trike up and running after several months, i have put in boyseen reeds, Uni filter and a full DG exhaust with DG muffler! I have done a carb rebuilt and put in the stock jets and about 2 turns out on the fuel mixture. I haven't checked the plug as I had to go out and my trike was hot after starting it! I know it's sposed to be chocolate colour! But every threat I have read they say put it up 2 sizes! Has anyone got an 84 250r with similar mods? What jet sizes are you running? Any help would be appreciated.
Thanks Ivan


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[yaegerb]

What's the problem?

[ivan-083]

I think it's running too lean. Sort of bogs down in first and second when I give it gas. I'll have to take a pick of the plug tomorrow and post up. How do I make it richer if too lean. Also I have standard jets are they too small of running exhaust and filter and boyseen reeds?


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[yaegerb]

Replied to your PM

[barnett468]

The plug does not necessarily need to be dark chocolate looking . In many cases, a 2 stroke is jetted closely if the plug is light tan.

Yes, going up 2 sizes on the main is pretty much a standard place to start anytime a stock pipe or stock spark arrestor type silencer is replaced replaced with one that is a "high performance" type.

It is always best to start with a rich setting and then jet it leaner until it is ideal then it is to start with a lean one because a setting that is too lean will quickly cause engine damage but a rich one won't.

An engine can also "bog" in the lower rpm range even when it is jetted perfectly.

The higher you are above sea level you are, the leaner it needs to be jetted but since 99.9% of Oz is near sea level, you probably won't have to worry about that.

Where in Oz do you live?



PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR

[350for350]

I can't say it any better than that Barnett.

[ivan-083]

The plug does not necessarily need to be dark chocolate looking . In many cases, a 2 stroke is jetted closely if the plug is light tan.

Yes, going up 2 sizes on the main is pretty much a standard place to start anytime a stock pipe or stock spark arrestor type silencer is replaced replaced with one that is a "high performance" type.

It is always best to start with a rich setting and then jet it leaner until it is ideal then it is to start with a lean one because a setting that is too lean will quickly cause engine damage but a rich one won't.

An engine can also "bog" in the lower rpm range even when it is jetted perfectly.

The higher you are above sea level you are, the leaner it needs to be jetted but since 99.9% of Oz is near sea level, you probably won't have to worry about that.

Where in Oz do you live?



PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR

Barnett
I Iive in Perth, this is the colour of the plug I had it running yesterday and just checked it now.
https://uploads.tapatalk-cdn.com/20170515/2662bb5b491d0b87bbcddb056acd27c6.jpg


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[ivan-083]

https://uploads.tapatalk-cdn.com/20170515/3cddaa408a9446ca877f8c1897bba717.jpghttps://uploads.tapatalk-cdn.com/20170515/aef2c72e30d39a7c69f34a246d852c44.jpg
This is with a new plug only rode it for about 4 to 5 mins as I ran out of fuel! What you think?


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[yaegerb]

Still looks rich to me.

[ivan-083]

Still looks rich to me.

What do you think I should do?


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[barnett468]

[IMG]
This is with a new plug only rode it for about 4 to 5 mins as I ran out of fuel! What you think?

I think you should put more gas in your tank. :)

On my screen it looks close to ideal and certainly does not look rich enough to me to cause any running issues like "bogging" but the color can look a little different on different computer screens . Irregardless, it is not black or wet looking or caked with rsidue.

I have a zillion things to do today so I can't post much now but I will post more later tonight if you don't get much more info throughout the day.

It is very hard to jet a bike over the internet because a lot of it is done by riding feel but here's a little info that might help.

In general, if any engine is rich enough, it will burble/miss/sputter etc when the throttle is opened . If yours does not do that it is definitely not excessively rich where big changes are required, however, it may still be slightly rich and only need fine tuning like one size smaller main jet and/or lowering of the needle etc.

When an engine is too lean, it will typically just hesitate some when opening the throttle but it should not burble/miss/sputter etc because there is not enough fuel in it to flood it.

As I mentioned, high perf engines are a different story and the focus on jetting these is jetting for the higher rpm range where they will be operated at because they often burble/miss/sputter etc in the lower rpm range when opening the throttle too far at low enough rpm . In other words, if you are going 5 mph in second gear with a high perf engine and then open the throttle all the way, it will typically run like crap and might even stall.

The more oil you use with the fuel, the darker the plug will be also.

A dirty filter or heavily oiled filter will cause it to run richer.

What oil are you using?

What ratio is it?

What is the number on your spark plug?

Do you ride it wide open much or just mostly cruise around?


I would also do a compression test with the gas off and throttle wide open . Kick it over fast around 6 times.

[ivan-083]

Using motul oil, 32 to 1 and using a br9es plug.
I'll put more fuel in it today and ride then check plug! Thanks for your help so far


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[yaegerb]

What do you think I should do?


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Check the pilot per the procedure I outlined in my pm. Get that correct first. Then move onto needle and main.

[ivan-083]

Check the pilot per the procedure I outlined in my pm. Get that correct first. Then move onto needle and main.

I have the 55 pilot and I'll put that in and see what you said!


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[atc300r]

Has your engine been rebuilt lately.Check your fuel vent on your gas cap.You should beable to blow threw it.

[ivan-083]

Yes it been rebuilt not long ago and yes I can blow through the gas cap.


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[magilla12]

I’ve been working on my jetting also, live in OK at 1500 ft. Stock engine full dg exhaust uni filter with airbox and holes in the lid. 138 main was too lean so I’m going to a 150 and do a plug chop. Honda synthetic oil at 32-1.

[magilla12]

I’ve been working on my jetting also, live in OK at 1500 ft. Stock engine full dg exhaust uni filter with airbox and holes in the lid. 138 main was too lean so I’m going to a 150 and do a plug chop. Honda synthetic oil at 32-1.

[oldoo]

Let me know what your results are Ivan, and ill jet mine accordingly after the same mods ahah :)

[elteee69]

Thanks for asking this question! I'm trying to dial in the jetting on my '84 also

[ivan-083]

Let me know what your results are Ivan, and ill jet mine accordingly after the same mods ahah :)

I just went two sizes up on the main and pilot from stock and that worked!


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