cf250 exhaust manifold too close to rear tire? By scooter2 (Read 1,632 times)

[scooter2]

I have a cfmoto Fashion 250. I was working on the exhaust and, after a ride, I noticed my back tire and rim were too hot to touch. I was really worried about it so I wrapped the exhaust with exhaust wrap material and, while that seemed to keep the tire a lot cooler, it's still so hot that I can't put my hand closer than about an inch from it when it's running, and there is only about 3/4 to 7/8" from the pipe, coming out of the engine, to the tire. Should I be worried? Anyone else notice this on their 250's? Can the tire take the heat?

[cyborg]

This is not good in my opinion,,, tires get warm even hot to the touch in summer but not to the point where you can't put your hand on it,,, I would make a heat shield or try and move the pipe

[jct842]

I would go one step further......I think that motor may be running lean. You should be able to hold your hand an inch from the pipe. Also would think about shimming the pipe out a bit too.

[rks]

You say your tire and rim are hot to the touch....and there is about 7/8" clearance between the tire and the exhaust pipe. I don't see how that would cause the heat build up you describe, at least not while you are moving...sounds like plenty of room to allow for air flow. Now if there was a hole in the pipe, blowing hot exhaust directly on the tire...that's different

If your tire and rim are truly getting hot, not just warm, I would sooner think that you have something else going on. First thought is a dragging brake, maybe along with an under inflated or overloaded tire. I'd be looking that whole rear area over, real good, blowing a tire on a two wheeler makes for a bad day.....maybe a bunch of bad days.

No tire should get so hot that it is uncomfortable to touch. Back in my trucking days, I used to place the back of my knuckles on the sidewalls to check tire temps at each stop. A couple of hundred miles between stops, and grossing 80,000+ pounds, tires get warm, but not hot to the touch. If one was warmer than its mate, then you knew it was carrying more than its share of the load, and that its partner was down some on air.

[richardv]

I agree that there's something wrong with the brake or bearings. The exhaust shouldn't cause such a heat build up.

[scooter2]

Mar 25, 2015 22:15:46 GMT -6 jct842 said:

I would go one step further......I think that motor may be running lean. You should be able to hold your hand an inch from the pipe. Also would think about shimming the pipe out a bit too.

 I can't really shim the pipe but I am also thinking it's running too lean. Other people on the net have said this is a cause of hot pipes. It's not the muffler, just the 8" or so long pipe leading to the muffler, especially the part closer to the engine. On one forum several people said they had the same condition and were not concerned about it.

When I got the bike, the muffler was broken at the pipe. I don't know if they landed on something or if they tried to set the bike on the muffler, but they broke it. I had it welded. I put in a new gasket and within three months the engine got loud so I looked and the gasket was gone. That's when I checked the tire temperature and found it was hot. I bought two new ones. I put in the first one and air was leaking out so I put in the second one. It doe cyborg jct842 rks richardv sn't seem to be leaking at all now but you can really feel the heat coming off the pipe. Now, even with the wrap on the pipe, it's getting hot. You can feel the hot spots on the tire and rim after letting it idle and spinning the tire around to feel it. After a ride the whole rim and tire is hot, noticeably hotter on the exhaust side, indicating heat is being conducted from that side to the other.

I will try upjetting the carb, but I'm also wondering if valve adjustment might cause heat to blast into the pipe? I'm using the external adjusters with the "listen for the clicking to stop and tighten it down" method of valve adjustment.

The bike runs great other than this heat issue, although it isn't lifting the forks up on takeoff like it did the first time I rode it. I am wondering if having the pipe welded caused some restriction inside the pipe. Maybe I should break down and buy a new muffler.

[Alleyoop]

If the pipe and or muffler are turning blueish color it is running really LEAN.
Alleyoop

[Alleyoop]

What I would do is check the rear tire for binding, So put it on the center stand and with your hands spin the rear tire. If there is binding it will be hard to spin then check the brake if not then I would suspect the bearing is binding.
Alleyoop

[scooter2]

Mar 26, 2015 21:40:33 GMT -6 Alleyoop said:

If the pipe and or muffler are turning blueish color it is running really LEAN.
Alleyoop

It's steel, painted black. The part near the engine has a reddish color to it and the paint is flaked away. 

[scooter2]

Mar 27, 2015 11:43:52 GMT -6 Alleyoop said:

What I would do is check the rear tire for binding, So put it on the center stand and with your hands spin the rear tire. If there is binding it will be hard to spin then check the brake if not then I would suspect the bearing is binding.
Alleyoop

When I spin it, it continues to spin. I don't know if it's really good but I'd say it's not bad either. Certainly nothing like a bicycle tire. It's a fairly new bike, an 09 with around 7k on it. I'm going to upjet it and see what happens. It was mig welded where the pipe meets the muffler, and I'm wondering if that may have something to do with heat build up as well, as it may have a little restriction on the way into the muffler, plus the baffle shakes around inside of it too. 

[Alleyoop]

Great so the wheel is not binding so then I would say that muffler is throwing a lot of heat onto the rim and tire.
Alleyoop

[richardv]

That little engine must be putting out some serious heat. Hope there's no serious damage done.

[scooter2]

Mar 27, 2015 18:29:08 GMT -6 richardv said:

That little engine must be putting out some serious heat. Hope there's no serious damage done.

Me too. I hope I don't pop the tire. That would be beyond scary. I upjetted from a 110 to a 125 and it runs fine. I'll take it for a cruise tomorrow and check the tires every few miles. If it's still hot I'll check the bearings and see about a new muffler.

[scooter2]

Mar 27, 2015 14:25:07 GMT -6 Alleyoop said:

Great so the wheel is not binding so then I would say that muffler is throwing a lot of heat onto the rim and tire.
Alleyoop

You are right. I cranked up my other scoot, a 250 Commuter, and, although it does get the tire warm near the manifold, it puts out MUCH less heat than the cf250 on this Fashion. On the Commuter I can hold my hand near the manifold as long as I want, and I can actually touch the inner side of the muffler with no problem, whereas the cf250 Fashion manifold is blasting out heat and the muffler is way too hot to touch.

I'm going to switch the mufflers out and see if that fixes it. 

[scooter2]

So... I switched the mufflers and no good. Still very hot. I even put the egr from the other bike on it and still no good. I then readjusted the valves, letting them click a little and still raging heat from the manifold. The bike runs great, but I am thinking maybe a leaking exhaust valve? scooter2,cyborg,jct842,rks,richardv,Alleyoop