[DRTracing]

It's a stock bore xr50 with ported and larger valves head. When I put it together everything is right, but it revs up slow not as responsive as it was stock. Do you think the stock carb is to small? if so what would be recomended? Maybe the 17mm???

 

[50man]

Why would you put a race head on a stock bore?

just curious.

 

[five0addict]

its the head, you dont have enough compression with that piston.

 

[DRTracing]

It's not a race head, just a stock head that has been ported and a larger intake valve. So I would think that the compresion would be un-changed.

 

[OLDSCHOOL]

Something is not right with your installation check it again.

 

[-eagle-]

Try a 62Mainjet in the stock carb.

 

[five0addict]

id say valve clearances, carb tune, or it is probly too much porting for the little 50cc motor

 

[DRTracing]

Ok I up'ed the size of the carb to match the port size it's a little better but not much. anyone have some ideas what else it could be?

 

[Jetster220]

Is the timing off, as that can really affect the power and revs.

 

[velocity101]

Since your port and valve sizes are a lot larger now ~ I'm thinking that your little stock piston isn't able to suck the volume of fuel/air mixture through the larger port passage ways adequately; especially at low engine speeds when piston is creating less suction volume.

 

[DRTracing]

do you think if I up the compression it will help?

 

[Jetster220]

Yes

 

[mxracer728]

do you think if I up the compression it will help?

yes

 

[Motarded]

go up with the compression, bigger main jet or carb, and put a cam in it, thats the only way you are going to use the bigger ports and intake valve.

 

[DRTracing]

This head was ported for a stock motor so I was told. but I have not been able to make it run right . I tried jetting, carbs,pipes that's why I was asking about the compression.power-roll has a 13to 1 kit what is stock? If this does not work right im going back to stock and trow that head in the trash. I think it should as fast as stock not slower like now.

 

[velocity101]

This head was ported for a stock motor so I was told. but I have not been able to make it run right . I tried jetting, carbs,pipes that's why I was asking about the compression.power-roll has a 13to 1 kit what is stock? If this does not work right im going back to stock and trow that head in the trash. I think it should as fast as stock not slower like now.

Don't throw the head away. Keep it for when you do upgrade to a big bore ~ it'll work much better then.