Tuning a B1 China replica

Expect to loose a little Rev's, But the extra power will allow for different gearing to even things out.

The difference between the squish you have now and 0.5mm should be really noticeable.

You can loose the base gasket, which will slide the whole cylinder down and get you closer to the correct squish, Make sure to measure a few different times, preferably measured all the way across the piston and inline with the Wrist Pin.

The only downside to correcting squish via the base gasket is, It will adjust port timing, On 9 out of 10 bikes The difference in timing wont cause any noticeable losses in power or revs.

And yes I'm sure the bearings will hold up as long as they aren't the china style, SKF is a GREAT brand.

Nick.

im using chinese bearings haha so maybe i should change them :P what will perform better how it is now or with low squish and higher gearin

Look at it like this, Lower squish, will give more power, which will allow you to use taller gearing and have close to the same takeoff speed, So I would say with the right gearing and the lower squish you can keep the takeoff speed and yet be able to have a higher top speed too.

Don't expect a miracle but it really does liven things up a bit.

Nick.

Let's not forget the importance of the setup on the clutch. The right springs, set to the best length, to engage at the best RPM's to launch, but when racing you only need it once.

my clutch springs are set to 21.8 and im 14 stone running 6 68 gearing

Sounds like just the ticket then eh.

i keep having pistons break

Jon you're also running a front tyre on the back which is a different profile and therefore makes your gearing different to normal??

woooo good work sam we managed to put my engine together and have a waterleak haha oh well still plenty quick enough to beat the other b1's at the track

the c1 b1 rep can run with the polini and the factory engines if you take time to tune it and if and when it breaks its a lot cheaper to rebuild i pay close attention to clearances to help it not to seize and well lubed and let it go full throttle

WOW......What a thread, I just read all 23 pages of it... Will be trying out the reed area porting and setting up my squish on my
B1 rep. I've already match ported it.

Has anyone heard of putting the standard clutches in the oven. I read a thread on another forum saying to put the clutch friction parts into an oven at 180* C for 45 min let them cool and do it again for 45 min. It's supposed to make them last far more than twice as long.

I think its meant to make sure that the glue has cured properly mate. Supposed to make the shoes less likely to rip off in the first couple of runs. Never tried it myself. I usually replace the circlips with proper ones tho. Proper euro springs are a good idea too. Most of the china springs start to go soft after a few runs.

I break-in my clutches in a little toaster oven. I start at 150 degrees for 10 min let it cool down.Than 250 degrees for 10 min let it cool down. Than 350 degrees for 10 min. Just turn the oven up when you pull the clutch out to cool down to pre heat for the next step. Havn't delaminated a clutch since but than again it's usally the first clutch when your first learning how to adjust them that gets messed up.

On my B1 rep I found a good starting point due to the springs having a mind of their own, to do the adjustment screws up to touch and then one whole turn in.

A good starting point is to set your springs to 21.5 mm and go from there.

choke performance in LA

Another way of bedding in the clutch is to just ride the bike gingerly for 5-10 mins or until it starts to get hot then shut down and let cool completely, you should do this for at least the first two full tanks of gas. Gingerly = no more then half throttle for short periods with mostly blipping to 1/4 throttle or just to the point when the clutch engages.
Upgrading the drum bell to the real deal (standard BZM 80mm) is cheap and has greater results then spending $160 for a euro clutch but still utilize the china drum.

Where are people buying the 80mm clutch drum here in the states?

midsouthminimoto

Thanks! My stock bell is a little out of round, and the pinion is off too. I bought another assembly (also stock) and it was just as bad!