squish clearance

[john durrill]

Chris , Thom,
 Did the post's help with your bikes?
Thom,  did this help with the how on the air jet circuit? Can you go into more detail on the ping , detonation problem you are having please?
 Chris, increasing the deck height is an  inexpensive way to lower the compression. As long as we dont go too far with it ( rule of thumb min .040 , max .060 deck height ) it will let us run our engines with todays pump gas and put less stress on the engine while still retaining the advantages of the squish band. Each engine is a little different even if the same model and year on how it responds to this. Some engine designs will actually make more power running lower compression and have a more linear torque curve. It is usually easier to jet an engine for a broad range of conditions ( like enduro , trail riding ,ISDTRR )if we are not on the edge of what is max allowable cranking pressure.
 I'm not a young man and find i still manage to learn something new every day folks chuckle chuckle. I do not know it all buy any means. I don't think anyone does. The whole point of this group is for each of us to help each other with the things we have learned over time. The good and the BAD things LOL!!All we can do it pass on what we have learned from our experience and things taught to us by people like Doug , Dane , Jack , Ron C. and many others. People that have ridden and worked with Pentons and the KTM factory .
 So keep asking till you are satisfied you understand it or have your question answered. The only dumb question is the one we don't ask.
 john d.
 
 
 

[Chakka]

John,
This post did help me quite a bit. Thanks very much for your input. Although you are very knowledgeable on all things related to engine work you always explain it in a way the beginner can understand it. I value your contributions and I wont ever be bashful about asking a question. My deck is set now to allow .040 on the l-ring dimension and I will be buying a MZ-B soon for that motor and will let you know how it works out.

Chris

[tomale]

John, I replaced the slide, needle jet, jet needle. The problem was the parts were worn out... evedently the these parts wear and need to be replaced with regularity. pinging problem solved.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
72'sixday (project bike)

[john durrill]

Thom,
 Follow this link. It shows the range of throttle opening each metering circuit in a Mikuni VM effects the most.
 http://www.flickr.com/photo_zoom.gne?id=2222335564&size=m
It sounds like the slide wear and the extra air from the cable entry were giving you a lean condition that caused the pinging. Because Bing and Amal use the same material for carb bodies and slides they do wear a lot more rapidly than Mikuni's chromed or anodized slides.
 The change from a vaporizer with many holes to a single hole ( like the 40-404) unit would effect a large range in the jetting. John's article shows that in the increase in jet sizes.
 Did this help with the question on air jets effect on Carb metering?
 John D.

[tomale]

Thanks John, yes it did, and yes, the air leaking in from around the cable and around of the slide did I believe the pinging problem, I knew about the soft slide being a problem  but did not know about the softness of the needle. Is that 40-404 vaporizer still available
what I know for sure is that my circle of  knowledge is growning smaller with each post, this is not a bad thing. thanks again!

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
72'sixday (project bike)

[tofriedel]

Thom,

Al B. had the atomizers and an eBayer, genuinenos, currently has them on eBay.

Tony

[tomale]

thanks....

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
72'sixday (project bike)