motomerlin

see my trials bike buyer's guide - aimed at Ebayer's but still usefull. Cheers, Mike

Usually the piston slightly siezes & smears alloy over piston rings, trapping them in place. To check remove exhaust pipe & shine torch up ex port. If lucky a stip & clean up will cure. If unlucky it's ripped the barrel coating and a replate & piston is needed.

Well worth re-packing. Do it regularly! Here's a guide I posted about the GG Pro middle silencer. The principles the same. Silencer repack the easy way!

Brief buyer's guide here: Trials Bike Buyers Guide

Shown as same part number as older Pros ....so it's a 6004 2RS.

Fronts are 6905 2RS ...cheap ones from guess where! Shock rose bearing is an odd size & so far only at premium price.

Ignore the drilling. See diagram here: Beta Carb Mod. Just alter float arms/tangs, that does it.

The forks will loosen up. But I found my 09 GG forks needed some work: I went to 2.5 w oil. And trimmed the plastic spacer (on top of springs) by 5mm. Also tried a different make of fork seal. Now they're pretty good. I tried a Raga & 2011 and the forks seemed fine. But bikes can vary....

I've got a couple left from current batch....call me tomorrow if you want one, Cheers, Mike

GG 2011 in action

I tend to use 450cc. ATF is fine. No dipstick, use the sight glass.

Chances are it's smeared the alloy of the piston trapping the rings - so low compression. Remove exhaust pipe & you can prob see this. Iff really lucky a clean up of piston would get it going. If not, plated bore may be damaged, so a piston & re-plate would be needed.

If it appears to change gear better going up the box than down, or vice versa, then the adjuster behind the clutch could need a tweak. GG USA have a video on youtube showing this. It's a fiddy proceedure, but should cure it.

Vic, Pistions are available here in the UK. However, you'd almost certainly need to re-plate the bore as well, after 11 years... Normally they re-plate to the new piston spec, and the letter is no longer an issue. Putting a nice new piston into a tired boke can be a false economy. Mike

6004 in the rear hub.