Hawk 250 Engine is Bogging

[jimwildman]

Originally Posted by Dallas

I actually watched this video about twenty times and it was very helpful especially since I've never tuned a carb. But now I don't "think" the problems in the carbs.

its most likly the valve lash, if you havent adjusted them yet, you need to, and get used to it. its part of the maintanence and should be checked on a somewhat regular basis. id say every 1000 miles might be about right.

its a known fact that they are tight from the factory, costing you compression and eventually causing burnt valves, usually exhaust.

it will click a bit more with some gap in there but will run much better.

ive seen anywhere from 4 to 7 thousands recomended. but any is better then none.

['16 TT250]

Originally Posted by Dallas

What valves are you referring to?

Intake/exhaust valves in the cylinder head.

[Weldangrind]

I'm with the others on tight valves. Still could be the CDI, but valves are free to check and must be done.

[Dallas]

Well I feel dumb. I thought that was the carb video. I'll adjust the intake and exhaust valves and let y'all know if there's any change.

[Electrotechnics]

You may need bigger jets in the carb. I had this same exact issue with a little 70cc Chinese bike. The plug was back and gas smell exhaust, but it was running so lean that the fuel couldn't burn fully and thus, looking like it was rich. I was convinced the bike was junk then I put in a #80 jet IIRC, and it solved all the problems. I dont have a hawk (yet ;D) but an 98 jet seems small for a 230cc engine, especially if there is any buildup or restriction in the jet.


Good luck!

[Dallas]

She lives!!

Ok so I adjusted the valves and just as everyone had said they were super tight! I set the intake at .003mm and the exhaust at .004mm. The engine sounded better but was still bogging down.

Then I put on the CDI I ordered and that made the biggest change! The bogging down stopped but it didn't have much power after the 1/4 turn.

I detached the air intake on the carb and she ran like a monster! So I pulled the filter and it had soaked up fuel and was restricting the air flow. I replaced it with a cheap mower filter and now she's running great.

I really wish I didn't have to use a filter. Without it she runs super mean and seems to put out more torque. Anyone have suggestions for a filter that would allow more air flow?


CDI
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Carb
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[Dallas]

Thanks for the help y'all!! Here's some Hawk tax.

[Ariel Red Hunter]

Originally Posted by Dallas

She lives!!

Ok so I adjusted the valves and just as everyone had said they were super tight! I set the intake at .003mm and the exhaust at .004mm. The engine sounded better but was still bogging down.

Then I put on the CDI I ordered and that made the biggest change! The bogging down stopped but it didn't have much power after the 1/4 turn.

I detached the air intake on the carb and she ran like a monster! So I pulled the filter and it had soaked up fuel and was restricting the air flow. I replaced it with a cheap mower filter and now she's running great.

I really wish I didn't have to use a filter. Without it she runs super mean and seems to put out more torque. Anyone have suggestions for a filter that would allow more air flow?


CDI
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Carb
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Great. It's running like a raped ape. Now keep checking that aircleaner. If you start getting oil on it, it is coming up the hose from the crank case to the air box. Cut the hose and put in a Positive Crankcase Valve in the line. Install it so that the engine pumps out air, but can't suck air back in. I've always run the hose back to drip on the INSIDE of the rear chain, near the countershaft sprocket. Also check out Motocheez's video on opening up the airbox - that can make a big difference in breathing.

[david3921]

Originally Posted by Dallas

Ok so I adjusted the valves and just as everyone had said they were super tight! I set the intake at .003mm and the exhaust at .004mm. The engine sounded better but was still bogging down.

Still might be too tight. Others are saying that it should be .05mm intake, .08 exhaust.

[Ariel Red Hunter]

Originally Posted by david3921

Still might be too tight. Others are saying that it should be .005mm intake, .008 exhaust.

I don't know about millimeters. But .03 intake, .05 exhaust should be ok. Inches, like we use in the United States.

[Weldangrind]

Originally Posted by david3921

Still might be too tight. Others are saying that it should be .005mm intake, .008 exhaust.

I agree. A little looser is better. To confirm, it should be 0.05mm intake and 0.08mm exhaust.


I'm going to edit this info and suggest 0.08mm for both intake and exhaust.

[Weldangrind]

Originally Posted by Ariel Red Hunter

I don't know about millimeters. But .03 intake, .05 exhaust should be ok. Inches, like we use in the United States.

When speaking in inches, it should be 0.003" intake and 0.005" exhaust.


I'll edit that and say 0.003" intake and exhaust, which equals 0.08mm.

[Weldangrind]

Originally Posted by Dallas

She lives!!

Ok so I adjusted the valves and just as everyone had said they were super tight! I set the intake at .003mm and the exhaust at .004mm. The engine sounded better but was still bogging down.

Then I put on the CDI I ordered and that made the biggest change! The bogging down stopped but it didn't have much power after the 1/4 turn.

I detached the air intake on the carb and she ran like a monster! So I pulled the filter and it had soaked up fuel and was restricting the air flow. I replaced it with a cheap mower filter and now she's running great.

I really wish I didn't have to use a filter. Without it she runs super mean and seems to put out more torque. Anyone have suggestions for a filter that would allow more air flow?

I wouldn't be seeking more air yet, but rather less fuel. What size main jet is in there now?

To answer your question, this is my favourite filter: http://www.ebay.com/itm/42mm-Angled-...xVG6hQ&vxp=mtr

[Dallas]

Let me correct myself. I set the valves at .003" intake and .004" exhaust.

The main jet is 110. I think I will drop it down to maybe 105 or 100. I'm still getting a bit of soot of the spark plug and around the end of the exhaust.

[Dallas]

Originally Posted by Ariel Red Hunter

Great. It's running like a raped ape. Now keep checking that aircleaner. If you start getting oil on it, it is coming up the hose from the crank case to the air box. Cut the hose and put in a Positive Crankcase Valve in the line. Install it so that the engine pumps out air, but can't suck air back in. I've always run the hose back to drip on the INSIDE of the rear chain, near the countershaft sprocket. Also check out Motocheez's video on opening up the airbox - that can make a big difference in breathing.

I think this might be a problem that's accuring. The liquid in the air box smells like gas but feels like oil. From what I read excess fuel will sometimes leak past the piston and into the crank case mixing with oil. Then build up and leak out.