61X Big Bore; LA Sleeve or Northwest Sleeve

[x2skier]

Does anybody know if there is a difference in port mapping between the LA Sleeve and Northwest Sleeve 61X big bore sleeves? I think I've read that the NW sleeves leave the option open for doing a stroker later becuase of lower port heights.....correct?
What's required, besides a stroker crank, to build a standard big bore 61X into a big bore stroker (4 or 5 mil)?

 

[#ZERO]

Does anybody know if there is a difference in port mapping between the LA Sleeve and Northwest Sleeve 61X big bore sleeves?

The big bore LA sleeve port timing is identical to the 62T stock sleeve which has 2mm higher exhaust ports when compared to the 61X stock sleeve.

The NW big bore sleeves are lower than 61X port timing which makes them good for freestyle or freeride and even racing applications when set up properly.

I think I've read that the NW sleeves leave the option open for doing a stroker later becuase of lower port heights.....correct?

Yes the NW big bore sleeves have a 2mm lower transfer port height which are extended down and can work well with 4mm or 5mm stroker cranks with the stock length rods.

What's required, besides a stroker crank, to build a standard big bore 61X into a big bore stroker (4 or 5 mil)?

The port timing has to be set up correctly for the desired engine application and some extra machine work is evolved depending on what parts are to be used. The cases may need to be clearanced or machined, the domes may need to be machined and the piston skirts may have to be trim depending on the type used.

Here are some dimensions of LA and NW big bore sleeves.

 

[Crab]

So are the NW sleeves ready ported to run once installed?

 

[#ZERO]

So are the NW sleeves ready ported to run once installed?

The sleeve itself is very close to being pre-ported but the cylinder casting will need to be extensively ported on the transfer, boost and exhaust ports. The transfer, boost and exhaust ports may still need to be altered depending on the engine application.

The main transfers are extended further toward the exhaust on an angle and the space between the main & auxiliary transfer is quite a bit thinner. Also the boost ports and exhaust ports are considerably wider than stock.

I've been making a few big bore 61X engines with these sleeves and porting the boost and transfer ports with the sleeves removed seems to be the way to go.

The exhaust ports are pretty easy to port match once the sleeves are installed.

Here are some pictures of a stock 61X cylinder with the sleeves removed and some after the porting has been complete.

 

[3rid]

Chris, by any chance, do you have the dimensions of the old R&D sleeves ?

 

[#ZERO]

Chris, by any chance, do you have the dimensions of the old R&D sleeves ?

They're very similar to the NW big bore sleeve specs and a lot more expensive

Also they came in two different size diameters depending on the pistons used.

 

[x2skier]

The port timing has to be set up correctly for the desired engine application and some extra machine work is evolved depending on what parts are to be used. The cases may need to be clearanced or machined, the domes may need to be machined and the piston skirts may have to be trim depending on the type used.

Would it be feasible to go with the big bore option first and the "upgrade" to a stroker at a later date? Or is it all or nothing from the start in regards to the stroker option?

 

[3rid]

They're very similar to the NW big bore sleeve specs and a lot more expensive

Also they came in two different size diameters depending on the pistons used.

Thanks for the info

 

[#ZERO]

Would it be feasible to go with the big bore option first and the "upgrade" to a stroker at a later date? Or is it all or nothing from the start in regards to the stroker option?

Each engine has to be set to a specific port timing specification.

The sleeves can be installed at different counterbore heights and the ports can be altered for each setup.

 

[jetski9010]

Each engine has to be set to a specific port timing specification.

The sleeves can be installed at different counterbore heights and the ports can be altered for each setup.

Bringing this one back. I had a question about getting the sleeves put in. So if I were to by these northwest big bore sleeves and want to run them with a 4mm stroker setup how do I tell my machine shop to install them? Or is that a builders secret?

 

[#ZERO]

Bringing this one back. I had a question about getting the sleeves put in. So if I were to by these northwest big bore sleeves and want to run them with a 4mm stroker setup how do I tell my machine shop to install them? Or is that a builders secret?

That's an engine builders top secret. :sneaky:

Those sleeves in a big bore stroker engine for freestyle will run well around 122 to 124 degree transfer duration and 185 to 188 degree exhaust duration. It helps to use a degree wheel when setting up the port timing for stroker engines. Most builders will use a TDC dial indicator with a degree wheel to find the best setup for the application as indicated in the picture below. You can adjust the port timing by changing the sleeve counter bore depth or milling the cylinder at the top or bottom. Also, pistons with different compression heights and different rod lengths along with changing the actual port sizes, etc., to find the best setup. So you might want to have a jet-ski engine builder do the machine work for you rather the having a local machine shop do the job, or you could puchase a degree wheel & TDC dial indcator and start measure the port timing.

 

[jetski9010]

I was thinking of sending my cylinders to northwest to have them install the sleeves or is that still not a good idea?

 

[jetski9010]

That's an engine builders top secret. :sneaky:

Those sleeves in a big bore stroker engine for freestyle will run well around 122 to 124 degree transfer duration and 187 to 185 degree exhaust duration. It helps to use a degree wheel when setting up the port timing for stroker engines. Most builders will use a TDC dial indicator with a degree wheel to find the best setup for the application as indicated in the picture below. You can adjust the port timing by changing the sleeve counter bore depth or milling the cylinder at the top or bottom. Also, pistons with different compression heights and different rod lengths along with changing the actual port sizes, etc., to find the best setup. So you might want to have a jet-ski engine builder do the machine work for you rather the having a local machine shop do the job, or you could puchase a degree wheel & TDC dial indcator and start measure the port timing.

What is the idea behind changing the port timing when you stroke a motor. Is the basic idea to lower the ports 2mm if your running a 4mm stroker. I am not trying to steal any secrets or anything but I have another project I am working for a buddy and he wants me to build him a 550 stroker motor. I was thinking of running a 3mm or 4mm stroker crank and then getting the bottoms of the cylinders shaved 1.5mm or 2mm to lower the port timing. The rings still have 5mm to the top so it would just be about cutting into the head to set up proper squish and comprssion. If I ran a setup like this would I even be close to where I want to be for freestyle or not? I was also going to widen the exhaust port to around 68% of the piston width and also trench out the transfer ports.

 

[#ZERO]

Benefits can be gained by increasing the port duration on the bigger displacement engines without sacrificing the bottom end for freestyle setups. Larger engines require more fuel & air to push those bigger pistons and crank around. When you stroke an engine it increases the dwell time at which the piston stays at BDC and this can have a dramatic effect on how long the ports stay open. The lower ports on the NW sleeves will help to correct this problem but you should use a degree wheel to find the actual port timing & duration before altering the actual sleeve and cylinder measurements. Also I'd stay around 66% on the exhaust width for freestyle because 68% is more race suited.

 

[jetski9010]

The big bore LA sleeve port timing is identical to the 62T stock sleeve which has 2mm higher exhaust ports when compared to the 61X stock sleeve.

The NW big bore sleeves are lower than 61X port timing which makes them good for freestyle or freeride and even racing applications when set up properly.



Yes the NW big bore sleeves have a 2mm lower transfer port height which are extended down and can work well with 4mm or 5mm stroker cranks with the stock length rods.



The port timing has to be set up correctly for the desired engine application and some extra machine work is evolved depending on what parts are to be used. The cases may need to be clearanced or machined, the domes may need to be machined and the piston skirts may have to be trim depending on the type used.

Here are some dimensions of LA and NW big bore sleeves.[/QUOTEI
I got a spare set of 62T cylinders that I was looking at the other day. I was trying to see if it was possiable to just copy the northwest sleeves as close as I can. It looks like I have 4.75 mm at the top of the ring wear to play with. I was thinking if I cut 2 mm off the bottom of the cylinders it would drop the exhaust port down to where it needs to be and then just let the piston pop out the top. Then when I went to measure the transfers it was not even close. Even if I cut 2 mm off to lower them 2mm I was still 5-6mm higher then what I needed to be for the northwest layout. Then it says the northwest transfers are 16.4mm high? How would the northwest sleeve work out on a stock stroke motor? Does it not uncover the transfer windows all the way? Also do you know the size fo the boost port window that the only one I cant see how tall it is. I am also wondering what the 8.88 is at the top?

 

[jetski9010]

The big bore LA sleeve port timing is identical to the 62T stock sleeve which has 2mm higher exhaust ports when compared to the 61X stock sleeve.

The NW big bore sleeves are lower than 61X port timing which makes them good for freestyle or freeride and even racing applications when set up properly.



Yes the NW big bore sleeves have a 2mm lower transfer port height which are extended down and can work well with 4mm or 5mm stroker cranks with the stock length rods.



The port timing has to be set up correctly for the desired engine application and some extra machine work is evolved depending on what parts are to be used. The cases may need to be clearanced or machined, the domes may need to be machined and the piston skirts may have to be trim depending on the type used.

Here are some dimensions of LA and NW big bore sleeves.

Sorry that got all messed up let me try again.
I got a spare set of 62T cylinders that I was looking at the other day. I was trying to see if it was possiable to just copy the northwest sleeves as close as I can. It looks like I have 4.75 mm at the top of the ring wear to play with. I was thinking if I cut 2 mm off the bottom of the cylinders it would drop the exhaust port down to where it needs to be and then just let the piston pop out the top. Then when I went to measure the transfers it was not even close. Even if I cut 2 mm off to lower them 2mm I was still 5-6mm higher then what I needed to be for the northwest layout. Then it says the northwest transfers are 16.4mm high? How would the northwest sleeve work out on a stock stroke motor? Does it not uncover the transfer windows all the way? Also do you know the size fo the boost port window that the only one I cant see how tall it is. I am also wondering what the 8.88 is at the top?

 

[SUPERTUNE]

The 8.88mm measurement is what the flange thickness is on the sleeve.
You can cut the counterbore less if you want place the ports higher in the cylinder.

 

[masterblaster]

ive ridden some nasty setup race boats with crazy bottom end with very high exh ports,im wondering if you setup a freeride boat with 124 transfers and went with a higher exh port like 195 or so nothing way high ,what is the motor going to do diff other than rev a little higher?

 

[waxhead]

your right on there master blaster
High exhaust does not always mean bad bottom end
High exhaust with bad setup means bad bottom end

 

[masterblaster]

wonder how well they would do without the tl? leaves me wondering what the 188 lower exh really does for you especially if its a rounded top exh port