Technical help with open air filter and new manifold.

DaelimRacer · Post by **DaelimRacer** » Wed Aug 10, 2011 11:23 pm

So along with the help of a friend we installed a new intake and larger 24 milimetre oko carb. We had wanted to install a big bore kit but it was the wrong size sadly.

More, sadly, we could not revert to the original intake as it was damaged while taking it off.

Anyhow long story short we had to install the larger carb and intake on the stock cylinder.

It starts up ok when I have the choke on full but when I turn the choke off it dies out.

I can ride it with the choke on but...when i give it about 60 percent throttle it dies out again.

Currently, it is using a 80 main jet.

I am thinking that because it is a larger carberator and using the open air filter that I need to go to a larger jet size.

But on the other hand if it runs ok with just a slight throttle and it dies out when I give it full throttle perhaps the mix is too rich.

Anyway, any thoughts on how I can resolve this?

DaelimRacer · Post by **DaelimRacer** » Wed Aug 10, 2011 11:25 pm

The original carburetor was 19 mm and the jet was 70 if that helps.

DaelimRacer · Post by **DaelimRacer** » Wed Aug 10, 2011 11:26 pm

Also guy took out the oil pump as well so does anyone know the ratio I need to use now.

Sigh............ the whole thing has been such a drag process.

jbcollier · Post by **jbcollier** » Thu Aug 11, 2011 6:28 am

Sounds like you need a larger main to me.

What's up with the old manifold? Could it be repaired?

DaelimRacer · Post by **DaelimRacer** » Thu Aug 11, 2011 10:43 am

it might be possible to repair the manifold but it does not connect to the new carb anyway.

so will try rejetting to see if that helps.

lesson learned

jbcollier · Post by **jbcollier** » Thu Aug 11, 2011 10:45 am

Run two percent as it is still a stock top end.

DaelimRacer · Post by **DaelimRacer** » Thu Aug 11, 2011 11:14 am

jbcollier wrote:Run two percent as it is still a stock top end.

Sorry what does this mean?

Yarko · Post by **Yarko** » Thu Aug 11, 2011 11:53 am

2 percent oil/gasoline mixture.

DaelimRacer · Post by **DaelimRacer** » Thu Aug 11, 2011 12:20 pm

wow! the guy here said 1:3 gas to oil which seemed kinda insane to be honest.

K that makes more sense then.

jbcollier · Post by **jbcollier** » Thu Aug 11, 2011 12:35 pm

2% is 50:1 or 50 parts gasoline to one part oil.

jaelee · Post by **jaelee** » Thu Aug 11, 2011 1:31 pm

you'll probably have to re jet the carb, there's a lot of information on the web about this topic. tuning is not a simple of taking off a part and putting something on. it;s a lot more involved and some knowledge is required. anyways...here's a start:

http://www.smellofdeath.com/lloydy/jetting.htm

DaelimRacer · Post by **DaelimRacer** » Thu Aug 11, 2011 1:48 pm

jaelee wrote:you'll probably have to re jet the carb, there's a lot of information on the web about this topic. tuning is not a simple of taking off a part and putting something on. it;s a lot more involved and some knowledge is required. anyways...here's a start:

http://www.smellofdeath.com/lloydy/jetting.htm

Ya I see that now.

fuck

jaelee · Post by **jaelee** » Thu Aug 11, 2011 2:00 pm

when i start a build i usually take the engine apart completely, match the cases to the ports on the cylinder. then match the intake port on the cylinder to the intake manifold, then raise the exhaust port and widen it to about 70% of the cylinder bore and match the exhaust port on the cylinder to the pipe i'm using. then i replace all the bearings and seals. I'll get it all together and almost do a dry build to make sure that everything "fits". i'll get on the web and research some gearing options. then get it all together again and fire it up. then the jetting begins. it;s a lot of work and takes a ton of time. and even after all this it's usually an on going project to make little adjustments here and there. just recently i got my lambretta to point where i'm happy with everything.

DaelimRacer · Post by **DaelimRacer** » Thu Aug 11, 2011 2:06 pm

K so just had an awkward conservation with a mechanic here in vancouver.

Guy said that by using an open air filter the mixture will change with temperature, and rain etc.. and I would never be able to use it. Which does not make sense to me.

I think he was just not wanting to get involved and looking for a way out.

Anyway so is my current situation just a matter of tuning then?
I know I went up a size or two on the carb but with proper tuning it will run correct?

Anyway overall a disaster of a situation.

jaelee · Post by **jaelee** » Thu Aug 11, 2011 2:10 pm

not necessarily, it may not run optimally but it'll work, and yes it's just a matter of tuning or dialing it in