First trackday of the year at Rockingham and all is going well.

I was concerned that it would not make the distance as I was told it had low compression and was running a bit rubbish below 5k.

I had nothing to worry about (yet) as it was a rapid little thing and it has a fast top end. Other 400's could not keep with it (or me ).

I do have a little issue with the carbs and need a new set. Does anyone have any??

I have also managed to pick up an 80% build sp engine for 99p on ebay (£17 postage). I’m just going you use it for the sp gearbox and cams. The plan is to build another 76 engine from spares for if/when mine goes pop. I am just looking for pistons and barrels.

Does anyone else track these who can pass on a few tips? I notice that I am revving the bike no lower than 10k round a track and most of the time it’s at 12-14. Can’t imagine that it will last long!!

Also it makes a tremendous howl!!

Could someone also tell me how to turn off the petrol tap?

I don't want fuel sitting in the carbs while standing

drain the float bowls if you dont want to leave fuel in it. Its vacuum operated so turns fuel on when it runs.so just need to turn to prime before you restart

Why do you need carbs? will a rebuild not do the trick.
You should be above 10000rpm most of the time
thats why the engine needs to be setup well with valves etc adjusted.
If you are serious about the fuel you can get pingle hi flow fuel taps that are manual on/off and get rid of the vacume but are about £80.

I was hoping the fuel could be turned off as it seems the flow when the engine is not running.

Also the mechanic done a great job setting it up but he said there was something wrong the carbs as it is leaking air. It leaks in on the rev down resulting in holding revs to long. He told me waht it is but I have forgot. Something has worn and would need replacing.

It's not a major issue but something I would like to sort.

i'm sorry to say your mech has done a crap job of setting up. if its holding up too long your idle mix is too lean

I do have a little issue with the carbs and need a new set. Does anyone have any??

I have also managed to pick up an 80% build sp engine for 99p on ebay (£17 postage). I’m just going you use it for the sp gearbox and cams. The plan is to build another 76 engine from spares for if/when mine goes pop. I am just looking for pistons and barrels.

Does anyone else track these who can pass on a few tips? I notice that I am revving the bike no lower than 10k round a track and most of the time it’s at 12-14. Can’t imagine that it will last long!!


what do you want to know?

I think my mechanic did do a good job. It runs very well it's just worn carb internals which are letting a small amount in. It's been on the dyno to get it running as best it can.

I have had a look at the fuel tap and I see it has prim, res and on. What is the diff between on and prim?

I was just seeing if there is any advice people can give for tracking them. Has anyone used an sp gearbox. I have one but running standard at mo.

Your bike should have a vacuum tap fitted, which overcomes the need to have an "Off" position.

"Prime" allows fuel to flow without the motor running / turning over. (by-passes closed diaphragm in tap)

"On" allows fuel to flow only when the engine is running (inlet vac opens diaphragm in fuel tap to allow it to flow)

"Res" operates under the same conditions as "On".

HTH.

Johnny wrote:I think my mechanic did do a good job. It runs very well it's just worn carb internals which are letting a small amount in. It's been on the dyno to get it running as best it can.

I have had a look at the fuel tap and I see it has prim, res and on. What is the diff between on and prim?

I was just seeing if there is any advice people can give for tracking them. Has anyone used an sp gearbox. I have one but running standard at mo.

all of mine bar one are sp's and tbh the gearbox puts so much pressure on the output bearing its unbelievable. Hard in town or in traffic where you need to filter. but great on the track where you dont slow down. now keeping the sp boxes for track only and building a new engine for the road bike with std boxes