p5yk0t1c

Here is the situation...My bike used to rip...I decided it needed more power so we installed the 5 port head kit (on a 911 rep) put it back together started it up and it sounded great. I haven't been able to test it out because of snow until yesterday. When I take off from the line it is super boggy...it feels like I have a 12 tooth front sprocket. Do you guys think it is my clutch? Do you have to adjust your clutch after installing the head kit? I would have thought it would be set perfectly from before. Once it built up speed...it would really take off...but the initial punch at the start is gone.

Any other things I should check?

Admin

Timing has taken a dive off the port bow. Squish isn't squished any more.

If you have an adjustable cluth you can try to adjust it to see if this makes a difference, I'm betting it's one of the above two items however.

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p5yk0t1c

We set the squish...to what I can't remember (0.5mm I think). How do you adjust the timing?

Wouldn't the above 2 things make my bike also sound like crap?

When we adjusted my clutch...there was a change in the bikes performance (for the better) but I didn't have time to keep playing with it.

Sleeves

Well KOS , gave me some wicked information on port timing , very interesting , wonder if it has something to do with whats happening to you !

http://www.tavia.com/free_degree_wheel.html

here is a degree wheel for timing , again this is all new to me , but maybe will help you as well ..............
Apparently you place your piston at tdc and place this cutout( the link ) on the flywheel , and by looking up the exhaust port , or with head off ( I am guessing on this one ) make sure thatthe piston is opening ports as says on degree wheel . then , you set squish !

Kos if ya want to correct me feel free !

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TRC , Amra , Mra , Smra
06' P1 BMS competition BZM 15.5hp Open 50cc
05' DM Telai - ZPF 18 h.p Open 50cc
08' CBR125r
96' Gsx-r 600

KOS

I am not 100% sure about the 911 rep, the only ones I have seen had polini motor swaps. But isnt the stock a 3 port and so you went to a 5 port?

So yeah Sleeves is right you need to start from the begining and see where you stand with timing, then squish etc etc...

But off the top the bog down low sounds like a needle adjustment or a jetting issue. That may clear it up enough to get that power back.

Your clutch is not going to make your bike bog... you are starving the motor of gas when it is boggin like that.

p5yk0t1c

Yes 1 thing we did was adjust my needle from second to the bottom....to second from the top. If that was the problem....would my bike still slowly build up speed (about 100 meters) and then engage and take off? Does that sound like a carb problem?

KOS

well this sounds like a different problem now than what I thought...you said in your first post it was super boggy, To me that means it is spitting and sputtering and makeing a bad noise...but you are saying that you start to move and it just takes forever to get up speed and hit the power band?

p5yk0t1c

Yes, exactly...everything was working great before we installed the 50cc 5 port. When I start it, it sounds great...It revs high with no load, but with load it doesn't want to move...that's why we keep thinking it's the clutch. Someone else was saying that I may have adjust my clutch because the 50cc revs lower at the start than the 39cc...is that true? I keep thinking it's my clutch, but I haven't had time to work/test it...I was just trying to see if you guys had some other input I could try. I didn't even think about timing...I will be checking that for sure. It just seems wierd that I have no power after installing the head kit.

KOS

ok so you went from a 3 port 40 to a 5 port 50....

now on a motor i just did we had something fairly similar. However it was just with port and case work and not changing jugs. I had done so much to the case and port that with a 40 or 50 starter/idle jet we had to run 110 main jet just to get enough mix to get it to run.....

we had similar symptoms as you..what size carb are you running, and what jets?

on the 40 we were able to get a couple laps out of the bike before the sun went down then we needed to rejet as the bike would no longer pull him at all, and after a while it would just die...way lean.

It would be interesting to see what carb and jets you are running and I bet if you start jetting up a lot you will recover some of that loss...however that is assuming when the bike was built the timing/squish was set right. You can adjust your clutch as well, but i am not sure that is it unless you have it engaging at like 2000 rpms

p5yk0t1c

I am running a 20mm Mikuni carb with the stock jets. Thanks Heaps for all your help, but we found the problem it was my clutch...everything is running sweet now. I was just stumped because I thought my clutch would be set perfectly no matter what the size of engine I had (39 vs. 50) . Everything else was set right.

Thanks for all help dudes!!! She rips...and I'm ready for the track