Yamaha YFM90RY exhaust question

[quadup]

This quad came with an Eton muffler and it has California emissions ratings on it, I took the guts out and tried just putting it back together without the restrictors in the exhaust. After having done that the Quad ran faster for just a short period of time (until it got hot) than it started to "bog down".

Any suggestions, not pleased at all with this Eton exhaust! I bought this quad for my son to race and am having a terrible time finding parts for a 90cc and any information anywhere.

Any suggestions or answers would be greatly appreciated. I also have several other questions but I will put them on seperate threads. Thanks for any help out there, or suggestions to fix this exhaust.

[LT80]

What machine do you have exactly. Rap80?

[quadup]

No it is a Yamaha YFM90RY, raptor, or in plainer terms a Raptor 90cc.

I am not sure now that what I did to the exhaust had any bearing on the quad's power. It had not been ridden since his last race, and have just discovered that something was put into his gas tank, possibly Powerade, or Lemonade, not really sure and no way of knowing for sure what was done to the gas , the gas had a very milky look to it and a sweet smell. I had my wife smell the gas and she says it smells like a mixture of gas and Lemonade to her.

I have now drained the tank and cleaned it with gas, but I thought what I had done with the exhaust was the problem so I put it back together like it was from the factory before we discovered that something had been put in the gas tank.

Just hoping that draining the tank is all I end up having to do...thankful he was sick last week and did not ride it any until today.

The quad was left unattended for a while, when we went to watch our older son race his Moto.

But still welcome any info or input you may have on the exhaust system and what to do to get more power...

Thanks for your reply look forward to any input from fellow riders/racers, bike enthusiasts, etc...

[LT80]

You need to clean the carb good. Remove both jets and the float needle seat and make sure all the holes are open.
Sounds like dirt in the bowl blocking a jet.
That's the first thing to do.

[quadup]

Thanks for your input. I have cleaned the carb. too and there was not any dirt in it, it was just milky looking gas and his brother has the same gas in his bike and I drained some of it to compare and his is clear and looks like gas should. I can't say for sure what was put in the tank, any guesses?

I have never seen gas that looked like this. It really appeared to have something put in the tank, the gas was very milky looking. Hate to think that someone would mess with a little kids quad.

Since we drained the tank and cleaned the carb. it is running just fine now, actually faster than it was when we checked him in his second moto last race.

Now back to the exhaust, I am stuck leaving it as is because I don't have enough to weld to, to take the guts back out of it...so I don't know exactly what I am going to do to it, I guess buy another muffler, any suggestions on the muffler?

Thanks for your help.

[nordic quad]

A few aftermarket available both slip on and full exhaust just make sure you are aloved mods in the class you run.I often use Ebay to find companys that make parts for the minis,just type Yamaha Raptor 90 and you will get a few options.You can also check out the mini secktion on raptorforum for more info on the 90.

Stein A

[LT80]

Glad it's running.
I'd give a 99.9% chance nobody added anything. Altho, at out 1st national in 1996, someone put a pilot jet in the fuel line of a competitors machine. Only 1 way it got there. Our machine was allways inside after that.
Pipes are a science. You just can't hack em up.
To be honest, the rap isn't a race machine. Maybe limit the money spent on this machine and if the boy likes racing, get him a machine more raceable.
ie: DRR/Apex

[quadup]

Thanks for your input but believe me I know more about pipes, than you could ever imagine, I was just commenting that I could do no more to that pipe... and wondered if anyone had a personal preference that was a great muffler for their mini quad!

This bike is just an experiment for my son, so we are trying to get the most out of it, because a Raptor is what he likes...and as far as the gas, yes there was something put in it, you said it yourself "Nationals" so "sabotage happens..." unfortunately some adults forget this is for the kids!

[marsrace2]

I beleive you can get some performance exhaust and other performance parts for that Quad from Justin at Maximum RPM. The reason the exhaust says Eton on it is because the whole Quad is built by Eton and Yamaha just puts their name on it.

[jandjracing]

Originally posted by quadup
Thanks for your input but believe me I know more about pipes, than you could ever imagine,

I know a couple of pipe specialists like yourself that have built thier own systems from scratch rather than relying on computer designed models. That's the route I would go if I had extensive knowledge on exhaust.

[LT80]

""The reason the exhaust says Eton on it is because the whole Quad is built by Eton and Yamaha just puts their name on it.""

Looks like there IS a Yamaha that I can recommend.
Good to know..thx.