Fairly new to Blaster a couple of questions

[cpq28g72]

My son recently bought a 1990 YFS200 from a garage sale really cheap. The guy told us that it had a knocking problem and would have to be gone through. we have been wanting to do a project together, so here was are chance.
Tore off the engine, rebuilt. New Wiseco crank kit, piston kit, bored .060, rebuilt carb,new fmf silencer. you name it we did it, and was really fun.

well it started on the first kick and sounded really great, except for the idle, wont idle. Thats when I read about the tors unit, so ordered that complete kit. still waiting on it.

But besides the idle problem, after about a minute of running it started popping
off and on, and I took it around the yard really slow after about 5 minutes of running and when I stopped It reved out of control and couldnt shut it off, so clutched it to kill it.
It started right back up and ran really good for a few minutes, and reved again, so I killed it again, started right back up and started popping and backfireing off and on again.

Maybe I screwed up a crank seal while putting it together, not sure yet.
I checked the woodruff key and its fine.

Just wondering if anyone had any opinions on this.
This is the first 2 stroke I have ever rebuilt, I have done many, many 4 strokes, with great success.

what a great forum, Thanks to everyone that helps out...

 

[brandoz28]

sounds like an airleak, build yourself a leakdown tester to check it out. the high rev is the tell tale sign. this could very well be your idle issue as well. did you retorque the head nuts and base nuts after riding it around for a little while? the reedcage area is pretty prone to leaking, a little RTV on the gaskets and you should be good to go

as for the popping/backfiring check the reeds.

did you put the full FMF exhaust on it? or just the silencer? if you replaced the pipe you need to rejet as well


good luck and welcome to the forum!

 

[blasterdad]

sounds like an airleak, build yourself a leakdown tester to check it out. the high rev is the tell tale sign. this could very well be your idle issue as well. did you retorque the head nuts and base nuts after riding it around for a little while? the reedcage area is pretty prone to leaking, a little RTV on the gaskets and you should be good to go

as for the popping/backfiring check the reeds.

did you put the full FMF exhaust on it? or just the silencer? if you replaced the pipe you need to rejet as well


good luck and welcome to the forum!

^^^^^^ For sure! Great advise!
When you stated you ordered a TORS kit did you mean one to eliminate it or rebuild it? Your best money spent is eliminating it. Welcome!!!, & keep us posted.

 

[cpq28g72]

Thanks for the quick reply, being new to these, every little bit helps.

I only have the silencer, used the stock pipe. I replaced it because if you shake it, it sounds like loose rags inside, and didnt want to take the chance with the new engine.

No I have not retorqued anything yet, but I will now that you suggested it. I went ahead and ordered new reeds, when I had it apart, they looked new but I didnt spend alot of time on them, so new ones are on the way.

Good thought on the reed plate, there was a spacerplate on it when I tore it down, and went ahead and put it back on, Not sure why its on there. some chrome thing, not stock. I will get rid of that also. and use rtv on it this time.

I forgot to mention that I also blocked the oil pump with a block off kit. and mixed the premium gas at 32:1 ratio.

Also forgot to mention the whitish smoke, didnt seem right to me. but I have never had a 2stroke before now.

Also while it was running, and I tried to adjust the idle it would go up and down all over the place, then got it to idle once and lightly tapped on the tors at carb and it reved up a little and died.

So it will take a few days for the parts to get here and try them out. I will post what I find. And how do I build a leak down tester and use it. I will search the forum for this, and Thanks so much again for your help in this matter.

 

[cpq28g72]

Yes I ordered the full kit to eliminate it. With the idle screw kit.

Thanks

 

[Zwiser]

how much white smoke

 

[cpq28g72]

Not a terrible lot, but enough to notice...

Thanks

 

[Zwiser]

ok sounds like a carb problem

 

[cpq28g72]

I rebuilt the carb with complete kit. Is there something I should do differently.

Anything specific that I should concentrate on in the carb?

Thanks

 

[Zwiser]

um idk since u rebuilt it prob a air leak and wat r ur jet sizes

 

[cpq28g72]

Main jet 220

Pilot jet 32.5

Thanks

 

[Zwiser]

ok its stock then so ur not rich umm prob an airleak then go to advanced auto and ask them about it

 

[Zwiser]

about an airleak tester not ur quad

 

[brandoz28]

1st thing's 1st, build and do the leakdown test, then go from there

 

[brandoz28]

ok its stock then so ur not rich umm prob an airleak then go to advanced auto and ask them about it

or search the site and find a great diy on how to build your own

http://www.blasterforum.com/do-yourself-20/build-use-leakdown-tester-10663/

 

[blasterdad]

Main jet 220

Pilot jet 32.5

Thanks

I'm pretty sure 230 is stock, so going up a couple of sizes might be a good idea, (better rich than lean!) try a 250-260 w/needle in the center slot to start with. Air/mix screw 1.5 turns out.

 

[cpq28g72]

Just found the post on how to leak test, I will do that.

Thanks everyone for all your help.

I will post what I find in a week or so.

 

[cpq28g72]

I found a 290 would that be to much?

 

[blasterdad]

I found a 290 would that be to much?

Try it, you won't hurt your motor running it too rich, but you will running it too lean! Better safe than sorry! You'll know if it's too big by the way it runs, (bogging,sluggish,when you nail it) & by plug chops. Read the sticky's on plug chops & plug color, you want it to be a light chocolate color.

 

[XxblasterboyxX]

i blew my oil seals and it was reving out of control after we fixed it. and i was missing this little rubber piece that goes over my clutch while we were waiting on the new rubber thing our shop guy told us to get somekind of oil and spray in that hole. and if it is still revving really high cant really remeber wat was broked though.