Should I run a 701 62t cylinder?

[romack991]

I'm building a new engine.

Currently I have a 62t cylinder with a fresh 81.5 bore with new pistons. I'm debating if I want to use this or to sell it and get a 61x cylinder or a 760. But then I'd have to get new pistons and more than likely have the replacement cylinder bored too.

The actual exhaust height on the sleeve is the same as a 61x. But the cylinder casting roof is roughly 3mm higher. Just wondering how much I loose in performance due to that step. The exhaust would be ported but I wouldnt raise the top of the sleeve.

Other Info.
I have both 62t cases with dual 38s or 61x cases with a single 44 laying around to choose from. Probably run a 61x electronics w/ lightened fly.

Whats a guy to do??? :shrug:

 

[sflsurfrider]

?

are those 61x sleeves in a 62t cylinder?

 

[SurfCrazed]

I have the same cylinder! 62T 701 and im going to run it!! bought it cause im cheap :biggthumpup:

 

[romack991]

?

are those 61x sleeves in a 62t cylinder?

I believe it is a stock 701 cylinder from a raider.

 

[romack991]

I have the same cylinder! 62T 701 and im going to run it!! bought it cause im cheap :biggthumpup:

well, if the performance is going to be noticeably worse from a 61x cylinder, I'd rather take the hit and build the engine up right the first time. But since its already bored and i have pistons, I'm hoping it wont be a big deal.

 

[SUPERTUNE]

No, Use the 61X cylinder for freestyle/freeride it will have much better bottom end. You won't need to to do a lot to one untill you have ALL the bolt-ons maxed out (44-46mm carb system, team scream pipe mods, better ignition and a lot of compression) then you can big bore sleeve/port that 61X and have a 781cc that will really rock off the bottom.

 

[WAB]

:noevil: I like my 62t cyl. My ports used to look like that, 94-95 Raider?
Isn't the port timing on these similar to those on the 760s?

 

[Mouthfulloflake]

Can you elaborate further SuperTune?

if the cylinder in the pic has the same SLEEVE as a 61x, how much different can it be?

No, Use the 61X cylinder for freestyle/freeride it will have much better bottom end. You won't need to to do a lot to one untill you have ALL the bolt-ons maxed out (44-46mm carb system, team scream pipe mods, better ignition and a lot of compression) then you can big bore sleeve/port that 61X and have a 781cc that will really rock off the bottom.

 

[SUPERTUNE]

No it does not have the same sleeve...Lower port timing all around, transfers and exhaust port heights.

 

[Mouthfulloflake]

Ill measure when I get home tonight the transfar ports, but I know for a fact that the 701 62t cylinder I have ( actually have had 3 of them)

has the same port height as the 61x sport port template.

thats the overhang of the sleeve vs the cylinder itself in his first photo.

weve discussed this at length, the eventual assumption was that in the 701 62t sleeves used in SOME engines, the same sleeves as 61x engines were used.

No it does not have the same sleeve...Lower port timing all around, transfers and exhaust port heights.

 

[Mouthfulloflake]

here is more info, and some pics of ONE of the three cylinders ive had that had this same exhuast port height , also , they were all stock, no port work done.

http://x-h2o.com/showthread.php?t=1924&page=2&highlight=62t+701

 

[romack991]

Measurements using calipers,
From top of cylinder to top of exhaust port, 39mm
From top of cylinder to top of transfer port, 55.5~56mm (sleeve is angled so value isnt the greatest.

If I had the bottom end together I would put the deg wheel on it but not there yet.

 

[Mouthfulloflake]

I hope to have time tonight to measure a 61x and a 62t cylinder with calipers and photo and post here as well.

 

[Mouthfulloflake]

ok, I had a few minutes to measure a couple of cylinders.

rough measure, cheap digital caliper.
I measured to the bottom of the square in the top center of a stock exhaust port.

61x=39.74mm

62t=38.89mm

0.85mm difference.

the sport port template I measured was taller than both of these.
so I assume, if you mark and grind the hole, you would remove any difference in exhaust port timing between a 61x and 62t cylinder ( its that slight)

I would LOVE for an expert, pro, or anyone with knowledge to step in here and further clarify things.

 

[feartheride]

So the 61x is the older 701 and the 62t is the newer one correct.I keep gettig confused.I was thinking the cyls.were the same and cases were diff.

 

[romack991]

All 94+ superjets come stock with a 61X cylinder.
The 94 & 95 had 61x cases. The 96+ has 62t cases.

The cylinder we are discussing is from the early Raider which has a 62t cylinder casting which has higher port timing but they seem to have 61x sleeves in them.

 

[feartheride]

thanks for clearing that up

 

[robertg]

I just did some measuring on a 62T 760 cylinder and compared it to a 61X Superjet cylinder. The only difference that I see is the exhaust port on the 760 is about 3.0mm higher. The only difference that I see in the transfer ports is the sleeves actually match the casting on the 62T cylinder. They are the same height from the top of the cylinder.

I ran the 62T 760 cylinder last year and the bottom end was pretty good as far as I am concerned. I am far from an expert but I would run that cylinder that you have.

 

[romack991]

I ran the 62T 760 cylinder last year and the bottom end was pretty good as far as I am concerned. I am far from an expert but I would run that cylinder that you have.

I am going to run it. Now the question is do I raise the sleeve to the cylinder wall (making it that 3mm higher) or leave it be at 61x port height and just leave the step behind the cylinder.

 

[SUPERTUNE]

Leave The Sleeve Alone! Don't Port Match It!