I'm in the process of getting my 701 engine rebuilt and noticed the sleeve/cylinder ports are mismatched really bad, is there anyone in NZ with experience in port matching these cylinders and maybe some performance porting as well?
sure are, they have the worst mismatch out of any stock boat. Check out the great sport porting thread on PWC today lots of info there on porting. MR Parker would be the man to speak to. You get more of a HP gain buy making the exaust port bigger than tiding up the Transfers.
Cheers Tim, I have talked to Roger and he confirmed pretty much what you said. Heres the link for the Sport Porting thread on PWCToday for anyone interested http://www.pwctoday.com/showthread.php?t=53981
thats normal for the 61x cylinder you can just align the porting if you like but the issue with the 61x is the lack pof port time area so there is alot to be gained by doing more than just cleaning them up the sport port is fine but its very mild
Since I'm waiting on parts, decided to give cylinder porting a go... My cases are already ported or I would have tried that too. Photos are in the rough stage just to show what was taken off. Have a bit of filing and sanding to do tomorrow, but took about 3-4 hours using a rotary tool with a HSS cutter I found at work.. The ports are to a RaceLogic template. Next time I will give a bit more 'tidy up' clearance when doing the rough cut, but came up pretty mint compared to the templates. I'm pretty keen to see if there is any difference, but thinking of raising the compression a little while I'm at it...
Looks good there is a few extra thinsg you can do You see the bridge between the two transfer ports you can drop that down up to 13mm as well as the sleeve this allows the sleeve to flow more while the piston is still coming down
Are you talking about the bridge between the two seperate transfer ports on the different cylinders or do you mean the small bridge seperating the two transfers? I didn't clean up the transfer ports as I don't have a 90 deg, The sleeve has already been dropped a lot, not sure how much, I guess about 10mm Timing... The stator is on the stock mark and I'm running a MSD Enhancer. What do you recommend for that? Not sure if I want to advance even a few degrees if I go higher compression too.. Ports are stock height (pretty much)
the blue and drop the sleeve to measure as well the transfers are very important you NEED to do them the weak area in a 61x is the transfer ports
I will try to get in there somehow.. That is good to know but my understanding is that will result in mainly top-end gains - possibly with some loss of bottom end.. I am primarily surf riding and only shortened the sleeve on the intake side in the first place because of my lack of mid and top with my current setup.. Also don't really want piston wear / ring wear to be any more than it currently is!!
I'm really going to have to upgrade my Mikuni 46 now.. Any pics of something I can copy? or you just go straight across? The ones I have seen are more of a loop...
Left a bit of a loop in it. About 8mm off at the back, 6 mm off front.. Again these are the rough ones
thats the idae and cut your sleeve down to help it breathe as well i cut the sides of the sleeve down 13 as well
All done now, almost ended catastrophically when the honing tool got caught in the newly widened exhaust ports... luckily it only damaged the tool. I think I'll take that as a sign to stop for the day! Exhaust, intake skirt shortened & notched, sleeve shortened ~8mm and managed to get to a couple of the transfer ports.
