G80 CS troubles

clive · Post by **clive** » Sat Jul 19, 2003 8:32 am

Are you sure about the timing? Running out of steam at full throttle and being hard to start certainly suggests timing problems (or carb of course). If it is carb problems then you have trouble with both the main and pilot jets in order to affect both top end and starting. Can you borrow a carb off someone's standard 500 which you know is set up ok and see if there is a difference? This would at least confirm it was a carb problem if the performance was much improved. If you live in london I could offer you a loan for a day or two. Good luck

RogerNorman · Post by **RogerNorman** » Sun Jul 20, 2003 8:52 pm

There are few people who have been succesful running a Mk2 or 3 Concentrics. They seem to run best on the Mk1. GP's are fine if you have got the time to muck around with them and can put up without a tickover.
Timimng is critical but if its running and starting then I would be more suspicious of the carb

ranger · Post by **ranger** » Mon Jul 21, 2003 11:28 am

Hi Peter I run a 61 G80CS and it is like a 'rat out of a drain pipe' when not breaking rocker arms; another story! Mine has a 389/16 monoblock with 280 main jet as it has an air filter and silencer fitted. The ignition timing is set, fully advanced -control lever forward, with the piston 0.458 inch before TDC. Spoke thru plug hole method. I just have the NC1 mag with points, good enough for me and easy to work on. It always starts easily without choke. My spark plug is a modern 10mm dia mid heat range NGK. I think with no silencer and airfilter the jet should be around 430. Good luck, Tim

silverarrow · Post by **silverarrow** » Mon Jul 21, 2003 12:19 pm

I would certainly check both ignition and valve timing before changing carbs etc. If they are both right then consider the carb. first is it completely clean. Any previous use with unleaded fuel could have left 'invisable' crystals behind that are partially blocking the main and/or pilot jets. On 2 separate bikes i have had this problem and the cure was very simple in cleaning the carb with a proprietory carb cleaner which can be bought from a car accessory shop. Use it in an open space as it is quite pungent. I am told but never tried that celluose thinners will do the same job but would not come in a handy spray can with nozzle to squirt up little orifices like jets. Lastly do you know if the engine has run with this carb before and properly? I also run a MK1 concentric with good effect. Les Smith

lawrence · Post by **lawrence** » Mon Jul 21, 2003 11:38 pm

I had similar trouble on my Bonneville. it turned out to be a poor connection on the electrics. The boyer is great but needs EVERY connection in the ignition circuit to be 100% (well soldered is best). i had one poor connection out of ten and that did it. you can short from the battery direct to the ignition as a test (ie. cut out the ign switch). Boyer have a very helpful tech dept, they really were good with lots of test suggestions. Once that connection was put right, it felt like a new bike! Hope yours does.