Jump to content
Sign in to follow this  

Big bore dilemma

Recommended Posts

Hey guys,

I just got a set of Hotcams for my birthday from my wife and I figured that now would be as good of a time to do the big bore as any. I have been staring at the Lukes Racing site and am struggling. Here is the dilemma.

Do I go for the Wiseco 440 kit w/ the 13.5 -1 piston for $550 or do I go for the JE 435 kit with the 13 - 1 piston for $415? How much of a difference will the extra 5cc's and 1/2 point of compression make? I dont mind spending the money if it makes a noticeable difference.

Thanks,

Craig

Share this post


Link to post
Share on other sites

Your going to have to run racing fuel with those cams and either one of those compressions.I just went with the 450 kit from Luke's.$600.00.Run the S base gasket and I can run 91 octane.If you run the E gasket you can run RHC cams with the higher compression piston,but since you just received the H.C. cams,you have to decide what fuel you want to run.Call Luke back he and his father were extremely helpful.Changing the base gasket provides fuel/ compression flexibility.Alex

Share this post


Link to post
Share on other sites

You won't be able to tell the difference between the two. 5cc is not much. Use the MT 94mm kit. Works great and they do great work.

Share this post


Link to post
Share on other sites

Ya, I know I will be in race gas territory with those compressions. I am hoping to get by with octane boosted premium on the street and then race gas for track days. This was quite a few years ago but Wiseco used to have a pretty poor reputation with their 4 stroke pistons. I have not heard bad things lately but stuff like that always sticks in the back of my mind.

I thought the 450 kit had issues with blowing head gaskets? If that isnt the case I would go for that one.

Share this post


Link to post
Share on other sites
Ya, I know I will be in race gas territory with those compressions. I am hoping to get by with octane boosted premium on the street and then race gas for track days. This was quite a few years ago but Wiseco used to have a pretty poor reputation with their 4 stroke pistons. I have not heard bad things lately but stuff like that always sticks in the back of my mind.

I thought the 450 kit had issues with blowing head gaskets? If that isnt the case I would go for that one.

The BB kits that use an iron liner have that rep.. Not aluminum liner that has been Nickel Silicon Carbide composite coated like OEM. Yes Wiesco had some issues,,,about a million years ago.... Nothing wrong with the product these days.

Here in TX, with the heat... You'll need some mix of high Octane gas to run a 13.5 CR big bore and Hot cams. Other cams with more overlap may not have an issue.

I've not found the off the shelf gas treatment stuff to work.I have tried at least 10 different brands, some just today, as I forgot do pick up some 110 leaded on Friday. I run a mix of 50/50 pump premium/110 leaded for most riding, up to full race gas if I need maximum quality, reliability of fuel stability and consistence.

Share this post


Link to post
Share on other sites
Hey guys,

I just got a set of Hotcams for my birthday from my wife and I figured that now would be as good of a time to do the big bore as any. I have been staring at the Lukes Racing site and am struggling. Here is the dilemma.

Do I go for the Wiseco 440 kit w/ the 13.5 -1 piston for $550 or do I go for the JE 435 kit with the 13 - 1 piston for $415? How much of a difference will the extra 5cc's and 1/2 point of compression make? I dont mind spending the money if it makes a noticeable difference.

Thanks,

Craig

So far I've run

90mm, 11.3 CR

90mm, 12.2 CR

90mm,13.5 CR

94mm,12.6 CR

95mm, 13.5 CR

All with Hot cams intake and Exhaust cams (the first designs,, not the new ones)

Some amount of race gas has been needed with all of the 13.5 CR versions. Power difference between 94mm and 95mm was, will little. Though the testing time was very limited on the 94mm set up.

As long as your BB has an NSC coated aluminum liner, JE or Weisco piston and the liner is installed correctly. All should be fine. I would not spend any extra $$$ on a 95mm vs the 94.5mm (both need a liner, so if same price, go 95)

If I was not repairing a damaged cylinder, I'd stick to the 94mm kit, which only requires boring and coating. No liner needed. Cheaper, and you'll not notice the performance difference . 94mm, 13.5:1 CR, Hot cams, yaaaa, you'll like that.

Share this post


Link to post
Share on other sites

Thanks for the info Bronco. I was planning on just doing the cylinder exchange with Lukes Racing. I dont want to have all of the downtime waiting for my cylinder to get back. I guess my decision is now down to the 435 kit for $415 or the 450 kit for $600. As long as the 95mm kit makes 2 HP more it will fit the $100/hp rule and be worthwhile.

Share this post


Link to post
Share on other sites

According to Luke and JE pistons it's a 95.5 mm piston not a 95mm.One of them told me bore x bore x stroke divided by what I now forgot comes out to 448.4 or 6 cc's.This piston is right of the shelf at JE,run the S gasket for pump fuel or the E gasket for racing.To the best of my knowledge they don't have 95mm waiting to be shipped.The way I looked at this big bore thing was I wanted the most cc's in a reliable package,I didn't care about another $185.00.I gained 50cc over stock,I got MT cylinder and a JE piston set. If I gain 6 HP,which I'm hoping,it cost me $600.00.If I want more all I have to do is change the base gasket,run racing fuel and put a set of Ron's cams in.I'm hoping that this will keep me satisfied.

Share this post


Link to post
Share on other sites
According to Luke and JE pistons it's a 95.5 mm piston not a 95mm.One of them told me bore x bore x stroke divided by what I now forgot comes out to 448.4 or 6 cc's.This piston is right of the shelf at JE,run the S gasket for pump fuel or the E gasket for racing.To the best of my knowledge they don't have 95mm waiting to be shipped.The way I looked at this big bore thing was I wanted the most cc's in a reliable package,I didn't care about another $185.00.I gained 50cc over stock,I got MT cylinder and a JE piston set. If I gain 6 HP,which I'm hoping,it cost me $600.00.If I want more all I have to do is change the base gasket,run racing fuel and put a set of Ron's cams in.I'm hoping that this will keep me satisfied.

Ya, thats a new piston from JE.... Have not used it.. 95mm was that largest not long ago,, and the place I trust MT,was not interested in using anything larger (ie 95.5mm) as the cylinder skirt gets mighty thin.

Share this post


Link to post
Share on other sites

I've got the 440 from Millennium, RHC valves and cams. I run 13.5:1 with 94 octane. The special Ron Hamp grind allows for higher compression with pump gas.

Share this post


Link to post
Share on other sites
Ya, thats a new piston from JE.... Have not used it.. 95mm was that largest not long ago,, and the place I trust MT,was not interested in using anything larger (ie 95.5mm) as the cylinder skirt gets mighty thin.

At some point in time I guess we will find out when reliability falls down due to the thin skirt. It seems like the 95 has proven itself to be reliable enough.

Share this post


Link to post
Share on other sites

Along the same lines, does anyone have any experience with the Yoshi big bore kit? I had my bike re-worked my Ben Spies crew chief due to my off time (broken leg first ride of the season) and got the whole works done. I've run Trick fuel mixed with pump gas for the first three years and never had any problems with the stock set up. Should I be switching to 50/50 race-pump or will my same old fuel mix work sufficiently? :thumbsup:

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×