A bit warm?

[geebt48cc]

So, 66cc skyhawk, 530 miles, Idles better than ever with better than average power. I've milled head down, and even not using a head-gasket (only copper sealant).

Ok runs wonderful, plug a lighter tan (NGK B6), but after 5 or so miles, she gets pretty hot. So, what ya think? ......Due to High compression? So, after 2 second touch to jug, it's very hot after first cut off. Using 25:1 synthetic....with a splash of Castor.......

Any ideas? It just might be the norm considering what we're working with here???????? I've always used speed NT...........

TY

 

[Deleted member 12676]

yes, high compression. If you still have a standard CDI then that also contributes to heat because it fires too early at high revs. You should enlarge the main jet just a tad so the extra gasoline will be a cooling influence.

 

[geebt48cc]

Jag, I know that it's a touch and go trying to find the larger jet size. What jet size would you start with on a 2010 66cc skyhawk with speed carb? Uno, next size up, or two from stock?

Thanks

 

[Deleted member 12676]

I wouldnt dare a guess. Use the current jet as your starting place and go from there. I give pointers on my site about how to jet the carb correctly, starting with the jet and then the needle position.

 

[geebt48cc]

Ok, well I'll find out size of original jet, and just increase it till I find right one to work. Wondering when I do increase jet size, if it will help increase rpm's to the better also?

 

[Deleted member 12676]

Sometimes an overly rich jet will hinder top rpms, but not an overly lean jet. Too lean is good for top rpm running but bad for acceleration. (ie: it has less grunt). Racers usually make it as lean as possible right up to the point of almost seizing.

 

[Ghost0]

Going to a higher octane fuel will also cool the engine a little. It will help reduce pre-ignition due somewhat to the timing issue mentioned and higher compression.

 

[geebt48cc]

Yes, I started out using higher octane which wasn't needed at time. Now that it's at a much higher compression, I'll try that again. Appreciate you waking me up to that fact. I'm sure that that can't do anything but help.................................

 

[Cali-Rider]

Sorry if this is slightly off topic but I had a few questions for Jaguar.

One is I have your newest version of your Performance CDI and I see two extra jumper terminals than the one in the picture on your website. Do you have instructions to the new version? Are the extra jumper terminals just used to hold a jumper not being used?

Two is; What are the ideal opperating temperatures for a 66cc at various locations? (ie; Spark plug, cylinder wall, exhaust port, and intake port)

Thanks for any help!

 

[Deleted member 12676]

I added another jumper to the CDI thinking to add more fine tuning. But now I kinda regret doing so because 99% of the engines out there arent high performance enough to be able to take advantage of that. Probably only engines that rev at or over 9000rpm could make use of that new addition.

As to temperature, most tuners just tweak the engine for maximum performance with a blind eye to temperature until it gets to be too much. Not sure about the acceptable limit but I think its around 500 degrees F at the base of the spark plug. Heres a link to a site selling a spark plug thermocouple. Looking at the manuals chart you would be able to translate the resistance of the thermocouple into temperature. (I want one!) https://www.pegasusautoracing.com/p...gle&utm_medium=productsearch&utm_campaign=gps