421 serval dome size

[stunter01]

Im on 5000 ft have a fresh built 421 serval built with vf4 and keihin 36 carbs. They send  me 17 cc domes with the kit. I get 175psi when i kick it over. Is this too much pressure im running on pump gas  95 oct. My squise is about 0.9mm. Want to use this bike for the dunes so if i go to sea level must i change the domes ? Sorry maybe this had been discussed before. Please help i dont want to break my engine these parts are very expensive

Thanks

 

 

 

[stunter01]

Anybody ?

[375hp banshees]

Don't run 17 @ sea level! Don't know if i'd only run 95@ 175 either. squish is on the tight side

Whatever you do , DONOT ask your Builder

[gusto]

I’ve got new 18cc domes and lightly used 21 cc domes I will sell if your interested.

[stunter01]

Thanks for the reply i also thought to rather fit 21cc. Will buy them from you anytime but im in south africa lol

 

[97Screamer]

I would run at least 100 octane at 175psi, possibly higher with timing. Yes you will need to change domes to run at sea level. 

[gusto]

4 hours ago, stunter01 said:

Thanks for the reply i also thought to rather fit 21cc. Will buy them from you anytime but im in south africa lol

 

If you pay the shipping I will send them anywhere. PM if you want them

 

i wouldnt run it with 100 octane I would go higher. Paying for race gas sucks, set it up for pump gas

Edited January 29, 2019 by gusto

[stunter01]

Thanks screamer im just riding it in at the moment just going low rpms. I was looking for a compression indication for pressure ratings on these oversize cylinders with different dome sizes but couldnt find. I forgot to mention i am on +4 deg also

Thanks gusto i found 21 cc domes locally was the last set . But maybe in the future i ll press your button 👍

[Schweet97Z]

What’s the highest octane you can get at the pump? I’m willing to bet we are dealing with the Ron/R+M/2 conversions here. Meaning his octane level isn’t really 95 like we would consider in the states but more like a 90-91


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[ClaudeMachining]

100LL is a good alternative to race gas.

Envoyé de mon SM-G965W en utilisant Tapatalk

[stunter01]

I think you are right it says 95 oct but could be a lot lower

Please tell me about your set ups , would love to get an idea

Which way i must go. At the moment im on 145 mains not sure about the size of the pilots but will check this weekend think they are to big . Bike was idling fine but when i test it the one side was running out of fuel so i adjusted both float levels and now the idling is worse than before.

Would it be a good idea to fit a pringle double outlet valve?

Thanks again for all the information

[Schweet97Z]

What’s your elevation? Is 95 the highest octane you can get? On pump gas and advanced timing like that I’d go with a 22-23cc dome depending on your elevation. I’d suggest a dual pingle so you don’t run your bowls dry as well.


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[stunter01]

Rode it yesterday after i adjusted the floats again . Elevation 5000 ft

Im on 145 mains at the moment going to fit 21cc domes over the weekend and check my pilot size because after the float adjustment the bike struggles to idle. Also need to fit a pingle i think. After that ill do a plug chop. It feels little dead on higher rpm

[trickedcarbine]

You’ll want 21-22 cc domes for that fuel. 

[stunter01]

I couldnt find only got 20cc will fit them over the weekend and check compression