I still could for example show the approximate dimensions пошня Ls 400, if you want to

Hi Paul, I too have a LS400 here in the UK. The bike is very much a mint looking bike. Only 5000 miles from new and I am the first owner since imported. I am also thinking of bigger piston and barrel. From what I am reading here, do I take it that the LS400 has a different crank/stroke to the LS650? or can I put a 650 barrel and piston with a head from a 650 (or can I keep mine?.) and that would run OK. I may need to re-jet the carb. Oh yeh, is the carb the same as a 650 bore wise?. Another thing is the decompression valve. The 400 does not have one. Could I fit one cheaply?.

paulmarshall wrote on 04/18/13 at 23:16:15:

tomorrow I drawing of the piston and shoot it and put in post. but in General I think, that the nearest option to increase the volume of the engine with minimal mods-Suzuki DRZ 400-- piston 90mm in diameter and approximately of the same form(so I thought) the piston pin it seems the same size.

[quote author=5275647764436D647272010 link=1366243636/15#21 date=1366400283]Hi Steve,I am yet to measure the 400 piston pin but according to Wambr they are different.Paladin made a very good point that due to our stroke being shorter, If we bored out to 94mm, (which is a stock 650 Bore) we would have a higher revving 484 cc. (I think.)
What I did was buy a 650 engine and bolted it right in.I did buy the wiring loom and carb, decompression unit etc. I only brought the 650 wiring loom because the 400 loom does not have a decomp unit.However u can use a manual decomp as I do now, so a 400 wiring loom will work.
The carbs are the same with smaller jets, so replace them.
The head is the same.
The other way which unless you do it yourself will $$$$, Split the bottom and fit new 650 rod and piston and Bore your barrall to 94mm. If your going that far maybe Bore out to 96 and use Verslagens 96mm Piston.


You say say the 400 has a short stroke so the only way I can see as to get the displacement up, is to fit a 650 crank as it must be a long stroke. No matter what combination of rods pistons, if the two engines (400cc and 650cc) have different stroke measurements, then the conversion is never going to get to 650cc. Does anyone think I am right in thinking this. I have always read from various forums that only the barrel and piston are different on the two engines. So If I can get hold of a second hand Crank, and rod and piston with barrel. I think I can get to 650 cc with re jetting of the carb.

[The stroke being the length of rod. The crank is the same as a 650. They would have used a different height piston in the 400.]

Easiest way is to bolt a 650 straight in like I did. However in NZ we pay more to register a 650 to a 400, So in the bigger picture I would save money if I plan on keeping bike long term. The bike would say 400 on the outside but 650 inside.

Our laws are very similar not surprising as we are all part of the commonwealth.

I don't think there is enough material around the cylinder sleeve on the 400 to bore it out and put a 94mm sleeve in it. At the very least it would considerably weaken the cylinder to the point of failure under stress. I have personally bored out several 650's ....there is not enough material in the cylinder sleeve to go larger than 95mm which is why when going to a larger bore like 96 or 97mm you need to bore out the old sleve and put a bigger sleeve in. 97mm is the limit on the 650's without weakening the cylinder. I have not heard of anyone going larger than 97mm on a 650...mine is 97mm. The cylinder sleeve and the actual cylinder need enough material left after the overbore for structural strength. I hope this helps, I would be careful about going to big on the bore on that 400...I have seen engine explosions cause leg injuries. I hope this info helps.