2007 Gilera Runner SP 70cc Starting Issues

Ghostt92 · L Plate Warrior Joined: 20 Mar 2016 Karma :

Hello guys/girls I'm relatively new to the bike world and I purchased my 07 gilera runner sp witch just had a full rebuild and has a pmtuning 70cc bore kit. The bike was abit boggy around 6-7k but I assumed it needed wearing in or it had been sitting around for a quite awhile but the bikes in good shape. The second day I went to top the bikes petrol up and 10 mins after that my bike died. So I took it too the garage and he done a compression test and it came back at 50 PSI witch he said was relatively low but the pmtuning is a single cylinder so I thought it was ok. so I changed the spark plug and she fired up! Then I took it for a test ride and the same thing happened again not long into my ride. So I thought it could have been the piston ring but to save boring you all here's a list of things I've changed and still has not fixed it. New piston ring,new race reed valve,new 21m carb with 75 main jet,new battery. The only thing I can think it can be is a faulty CDI? But apparently they either work or they don't? my bike is getting spark but I don't know what's a good spark or not. Or could it be my oil pumps had it? The bike sounds really healthy when it starts with manual choke but it revs on it's own then bogs down and dies and gives a slight little popping misfire at the end! Please help me!!! If you want to know anything else about the bikes behavior feel free to ask.
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Gilera Runner SP

Taught2BCauti... · World Chat Champion Joined: 12 Jan 2012 Karma :

50psi is very low - I would get it checked again.

Either go somewhere else, or buy your own compression tester (cheap enough on eBay) and do it yourself.

If the compression really is that low and the piston and rings are good, and the bore is not badly worn or damaged, I would suspect a head or crankcase gasket leak.
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Honda Varadero XL125(V8)
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Ghostt92 · L Plate Warrior Joined: 20 Mar 2016 Karma :

update-- After all the money I've spent it turns out it was my CDI after all. now I'm putting a stage 6 bore with Kevlar belt with a few extra bits and get a 17.5mm 19mm carb. I'm thinking maybe I went too big on a 21mm carb with my current setup.
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Gilera Runner SP