Rpm cut at 6k rpm

[Kart801]

Motor idles fine and stays running seams like its getting plenty of fuel also. When I get going around the track it doesnt want to turn higher than 6000. Seems like its hitting a rev limit. Doesnt feel like floating valves. I adjusted the idle air screw on the side to half a turn out from all the way in and that seemed to help but still not running properly.

 

[OVALTECH1]

That screw should be 2 1/2 to 3 turns out. Explain the problem a little more does it just nose over with its tongue hanging out or does it cut out a bit and get herky jerky? What jets ? What cam and head ? Also.... how big of track and what gearing ?

 

[DynoDon]

Do you know what the cc is? Is there a chance you have a blown head gasket? Your springs could be collapsed, or you installed height could be wrong. Engine timing could have slipped.

 

[Kart801]

Bought the motor from a guy from a buy out. So I dont know what the specs are on this thing. Have one more race for the year and was hoping to use it one more time before sending it off. Basically the engine feels like it wants to go faster just in able to. Wouldnt say it gets jerky but mayb tongue hangn out like my dunkn just never gets the dunk haha. Track is 1/10th mile I was probably off on gearing but it was my first night on a clone and was guessing on gearing but without the engine running properly its hard to get the right gear. 16/84 219 chain. I think of I was on a 15 or 14 it may have been better.

 

[Curflo]

More than likely you are off on gear

 

[Kart801]

That would cause it to misfire? Even when not on the track it wouldnt get much above 6000 rpm on the stand. Would miss and sputter all thw same.

 

[GClary]

Don't know what class you race , but your off on gearing . The more details you post , such as pipe , jets , cam info , ect . , helps us help you . I would say as Don mentioned , springs , timing , dirty carb are all things to check .

 

[Kart801]

Adult clone heavy. As said before I'm not sure of the cam jets and pipe bought the motor from someone who didnt know much about racing and I just started back up. I'm kind of clueless about these clones as I ran briggs alcohol back in the day. Where can i find the info you need on the cam? I'll try to take the carb apart when im pff work this morning. The pipe looks like a common one used I dont know if u can tell by this picture what pipe I have?

 

[flattop1]

Looks like a standard out the box clone engine .
It may not turn much over that .
One race left , try too get the valve springs changed .
A new plug , then drop 5-10 teeth off the rear gear for hot laps see where your at then .

 

[IndyHarry]

That would cause it to misfire? Even when not on the track it wouldnt get much above 6000 rpm on the stand. Would miss and sputter all thw same.

Sounds like a jetting issue. This can be verified by the color of the plug.

 

[Kart801]

Plug is black every time after the race

 

[IndyHarry]

Plug is black every time after the race

Yep might have to pull the jet and see what size it is. Definitely too much fuel. Plug should be a coffee brown color.

 

[Kart801]

Does Tom rayl still build engines?

 

[IndyHarry]

Here is a basic how too video of jetting and how to change it. If your interested. It's pretty easy.

 

[Kart801]

Yep might have to pull the jet and see what size it is. Definitely too much fuel. Plug should be a coffee brown color.

Looks like 35 jet and 7 on the low speed?

 

[Kart801]

Dont have a tool to check springs but they appear to have no markings and "look" stock

 

[IndyHarry]

Looks like 35 jet and 7 on the low speed?

My guess is its been drilled. The number seems too small and doesn't match the plug. Some racers change springs every other race. It helps to roll the engine over to the compression stroke so the springs arent staying compressed. New set of springs sure wouldn't hurt and verifying the jet with a sized bits or pins would be very helpful.

 

[flattop1]

Does Tom rayl still build engines?

I thought he got out . Maybe if your one of the lucky ones .
Springs are a key component .
Also there o-ring is missing on the low speed jet .
Some carbs are ran that way .
If it's the 3910x try a standard plug .

 

[DynoDon]

Anyone who changes springs every other race must have deep pockets. If it ain’t broke don’t fix it.

 

[IndyHarry]

Anyone who changes springs every other race must have deep pockets. If it ain’t broke don’t f

Springs loose tension from the time they are installed and limit rpm through valve float. If you want to go 4 races instead of 2 before changing them then use the red Strip ones.