J motor max displacement

Speaking about maximum displacement I was just talking to the guy who does all the drag race engines in my local area. He said he has done four 1500 blocks for different clients in the past couple of months.

He mentioned 1500 is now consider on the small side, its what guys use for "weekend" bracket racing. Engines ranging from 1640 to 1850cc's are what Pro's are using now.


 

Thank you.

I have almost zero interest in a dedicated drag bike.

But maybe a 1500 could make a bad ass mountain road sleeper?

RedPill wrote:

Thank you.

I have almost zero interest in a dedicated drag bike.

But maybe a 1500 could make a bad ass mountain road sleeper?

it's a nice idea but I suspect you would end up with an overheating, leaking unreliable money pit - there is a reason why motors built to run 10 sec at a time on throttle don't find their way onto the street  (IMHO)

so I would not advise anybody to build a 1260 for street use.

A 1075 engine is plenty strong and a lot cheaper option

 

Agree 100% with @Injected.  A well built 1075 will provide plenty of reliable power for the street.  

Mike

RedPill wrote:

Thank you.

I have almost zero interest in a dedicated drag bike.

But maybe a 1500 could make a bad ass mountain road sleeper?


 

Sorry to burst your bubble but anything 1327cc and above requires a big block which does not have any provisions for cooling like a stock block does. Even "cheater" blocks have minimal cooling fins on the block and no pass thru holes around where the liners are pressed in.

Above 1428 they require much higher lift cams than are recommended for street use to run properly. Even the bigger RS40 flat slides are on the small side for a 1500 engine build.
1500cc is a 85mm piston, it pretty well max'd out the area on a big block. MTC does sell pistons out to 89mm but I believe that are for billet blocks only.

Below is a 85mm piston in a big block :



With small cams (.435") and carbs that 1500 would run like a tractor. They don't sound right unless they are set up for full air flow potential.

Guys do run 1428 big blocks on the street but they are not meant for that so there are bound to be issues. There are all kinds Pro Street bikes out there but they are mostly built for bragging rights.

Injected wrote:

 

Sorry to burst your bubble but anything 1327cc and above requires a big block which does not have any provisions for cooling like a stock block does. Even "cheater" blocks have minimal cooling fins on the block and no pass thru holes around where the liners are pressed in.

It's actually anything over 1260 that requires a big block and even at 1260 the liners break through the stock casting which is why Wiseco and others have dropped to 1200 and slightly smaller OD liners as the max for a stock block to prevent this and the associated oil leaks.

zed1015 wrote:

Injected wrote:

 

Sorry to burst your bubble but anything 1327cc and above requires a big block which does not have any provisions for cooling like a stock block does. Even "cheater" blocks have minimal cooling fins on the block and no pass thru holes around where the liners are pressed in.

It's actually anything over 1260 that requires a big block and even at 1260 the liners break through the stock casting which is why Wiseco and others have dropped to 1200 and slightly smaller OD liners as the max for a stock block to prevent this and the associated oil leaks.

 

I have a Wiseco K1172 piston kit ready to install in a stock ZN1100 cylinder block that was bored out to 75mm.
As I understand, 1170 is the largest piston option Wiseco offers for a Kaw 1100 (1089cc) engine, unless bigger sleeves are installed and the case is bored to accomodate them.

I'm hopeful this motor will run cool like the old '82 with the MTC1135 kit does, but do wonder if I should be prepared for unanticipated surprises.



 

zed1015 wrote:

Injected wrote:

 

Sorry to burst your bubble but anything 1327cc and above requires a big block which does not have any provisions for cooling like a stock block does. Even "cheater" blocks have minimal cooling fins on the block and no pass thru holes around where the liners are pressed in.

It's actually anything over 1260 that requires a big block and even at 1260 the liners break through the stock casting which is why Wiseco and others have dropped to 1200 and slightly smaller OD liners as the max for a stock block to prevent this and the associated oil leaks.
 

Thanks for pointing that out.
I just checked a old Wiseco catalog and it states that a big block is required starting at 1230cc (77mm piston) I guess that size has dropped off the radar.
I can totally understand that as a 76mm piston leaves .100" liner thickness on the sleeves required to fit a 1197cc kit in standard 1015cc barrel.
I know you can go down as far as .080" on the liners for racing purposes but more meat is preferred for longevity especially for street riding.
At .100" liner thickness I will be running a large oil cooler.


 

So in the video, the Tsukuba monster class guys say they’re getting 120 - 130hp.

How difficult is that with a 1075? How about with an 1170?

Can most any competent engine builder accomplish this?

Porting, cams, bigger cams, exhaust, welded crankshaft, some kind of kit that makes it shim under bucket. Bigger carbs. Anything else?

I have five 1075cc Zeds.
1 turbo, 1 supercharged and 3 on carbs.
The 3 carbed bikes are daily riders in slightly different states of tune but not over done, idle nicely and pull smoothly to the redline. 
None have cams above 410 lift and run shim on top with carb size ranging from vm26's bored to 30mm and vm32mm oval bores from 1000 Katana..
I built them all myself from the ground up including all engine work.
I've never had them dyno'd but all three will top 160mph which equates to at least 120hp to achieve that with these engines and the unfaired prone riding position..
 

RedPill wrote:

So in the video, the Tsukuba monster class guys say they’re getting 120 - 130hp.

How difficult is that with a 1075? How about with an 1170?

Can most any competent engine builder accomplish this?

Porting, cams, bigger cams, exhaust, welded crankshaft, some kind of kit that makes it shim under bucket. Bigger carbs. Anything else?



 

First of all your quoting HP numbers from track engines on race gas, not street tuned engines on pump gas. You should post a link to the video as there are many classes and some are unlimited displacement which makes a big difference.
Even if the class limit was 1200cc you can't compare that to a street tuned engine as you can run a lot higher compression on race gas.
Pump gas limits compression ratio to about 11:1 (air cooled 2 V) most race engines are 13-14:1
HP will be variable due to port size, valve size, carb size, cam lift, and compression. HP can vary on the same displacement engines by as much as 30% (rough est) due to the components and state of tune between them. Every engine is going to be different depending on how much $$$$ you throw at it.
In all cases of hopped up engines you would want a welded crank. With cams over .410" you would want shim under tappets, there are no "kits" to make it that way, you just set the valves up to be able to use that type of bucket.