Rijko

Black box, the original igniter box ? What setup was that, Dyna S ignition, coils and leads, hooked up to the OEM igniter box ? Or a Dyna 2000 ? I have seen issues with that one. Great system, rare to have problems but can go bad. I aided a buddy with one bad unit, have to say Dyna support was super. Knowledgeable, the guy owned a GS1000 himself. And testing the Dyna 2000 which was bad, and offering a great deal on replacing the out-of-warranty unit.

GS750 oil pump gears improve oil flow. Replace the weak original clutch hub nut with the stronger GS1150 one (https://www.cmsnl.com/products/nut_0914024014/) They tend to come loose, not with the GS1150 one or the more expensive APE replacement. Choose the best starter clutch, most are damaged. Compare your camshafts, some GS1000 models came with some .5 mm higher lift ones. Check the cam chain is not stretched. Slotted cam wheels, degreed, wake the bike up. As do carbs like Mikuni VM29SS smoothbore or Keihin CR. Personally i would overhaul the original cam chain tensioner. That's just replacing the o-ring and oil seal, easy job and cheap. The automatic one works great and is very robust. Choose the best stator, some are really burnt or already failing.

This should help https://www.ozebook.com/compendium/suzi/engine-nos/engnos.htm

Do all B12 have that ? I have a 2004 B12

Great bikes, this is one of mine

Have experience with that ? I would be very interested. I have the same issue with a Moto Martin. These tanks are small to begin with, so a tank in a tank would reduce fuel capacity even further. Fortunately Martin sells the tankseats still, in modern material that can handle modern fuel. Think i'll go that way. But if you know of fuel blatters or something else ... lemme know please.

I think that's the way to go. Mate had one made by TheTankShop in Scotland IIRC. Price was nice, took half a year though. Was delivered polished like chrome, no dents or scratches or imperfections. Best alloy tank we have ever seen, perfect replica, perfect welds, so beautiful he did not paint it.

i would not risk it, coating does not hold well on polyester tanks that had gas in them for years. Talked to my painters over the years, they warn their customers about that. I ended up having mine reproduced using modern material that withstands modern gas. Not too expensive, too. Ofcourse after i done that i found a NOS tank, lined and painted ... the guy spent all that money only to find out he had the Kawa tank with petcock positions different to the H*nda and had it just sitting there

How did you spray starting fluid into the non firing cylinder ? These VM carbs do not like to run without airbox much and you sayin' hand against the carb makes me ask. What happens if you start the bike and spray some fluid into the nr. 3 vacuum hose with the airbox on ? Does applying the choke on and off and giving it a bit of throttle make any difference ?

Since we're kinda guessing and you have already taken off the head, reground valves etc : assuming you set valve play and rechecked compression .... Did you replace the o-rings on the carb-to-cylinder boots ? Maybe test the seal on number 3 by spraying brake cleaner or starter fluid on the boot. Any change in rpm, up or down, indicates a leak. Are the 4 carb sync bolts in the inlet manifolds present ? Got a strobe light ? Neat use for that thing is connect it to the problem cylinder and just look at the flickering light, no need to point it at your timing marks. Multiple issues like a broken spark plug, cap, bad connection to the cap, etc show up clearly. Either by not flickering at all, or clearly irregularly. Stuff i would not have noticed because i saw a nice spark were clearly visible this way. Got a 'known good' situation where the bike ran on all 4 ? Maybe with the points setup ? Got good 12V at the ignition and coils ?

Cool build ! Is that an original (polyester) racetank ? (vs wider "coffin" metal gas tank and dummy tank on top) That old polyester stuff does not handle the modern day gas very well ... may want to consider that before spending a lot of money on painting.

You did not mention replacing the base gasket and o-rings. These will often develop a leak when disturbed by taking off the head.

The fuel tap vacuum hose is on nr. 3, is it connected to the petcock ?

According to the document, there are at least 3 types of cams : 100/111/125 HP, the D cams being the faster ones.

This is a super study into the cams, start at p29. Sorry, it's in German. https://up.picr.de/36612796ge.pdf