SRX 400-600

[CHRIS211083]

hi all, i was wondering if anyone has attenpted this before??? i have a 87 srx400 with 21k on it but im 6'5 and 20stone (but athletic). so i could do with some more ponys. i have a 600 motor which i intend to breath on a bit. love the bike, this is my second. any info on the engine swap would be great!!! anything at all. cheers chris.

[Steve Lake]

if they are both twinshock lumps (assuming your chassis is twinshock) then it's out and in no problem, done it many times on my 600 (when i take the lump out to fettle it, and stick a spare 400 in to keep me mobile) do you have a twin front disc setup?.....not that it really matters if you havn't....a single disc will pull up a 'breathed on' 600 fine, just have good pads and braided hoses.
I only have a single disc on the front of both my srx6 track bikes and it's fine.

good luck with it

what do you plan to do to the engine?

[CHRIS211083]

HI, yes both twin shocks. was going to have a wiesco 1mm oversize piston, a new con rod (standards ive heard are weak) with 11.5-1 comp. and a gas flowed head. i was thinking of 33mm crs carbs. what do you have done to yours steve??? im not going for power more a balance of more power with good reliability and mpg? i know the cr carbs go to 37-35-33-31 but what do you think wound give the best results? is there anything else you would recomend???

[Steve Lake]

my road srx6 has a stage2 head done by the 'cylinder head shop'......max bore with 10.5:1 piston gives approx 630cc, initially i ran it on a single 40mm dellorto on a handmade manifold.....standard rod (not...as far as i'm aware.....a weak item as long as you respect the rev limit) however, i did ream and sleeve the little end and have new mains and big end fitted. Does everything  i want....really tractable, plenty of grunt, and will cruise all day at 85-90 (I have fitted the largest sprocket that'll fit on the front, which works very well with the extra grunt, 5000 revs = 80mph.)

currently running twin 35 dellorto's....which are good too.....but i still need to jet them correctly, bit lumpy at tickover.

my srx6 engined track bike is a different story...

Also check Andy230's efforts on his supermono racer....a wealth of experience there....ending up with a stonking motor

[CHRIS211083]

How much did your head work cost??? did you stick with standard valves??? and the 630 bore i have not seen, where did you find it???

[Steve Lake]

200 quid....standard valves

whatever a 98 mm bore works out at, get  the piston from wiseco and the oversized gasket...about 100 notes