thanks Houston, whats the difference performs wise between the two? i'm looking at getting another engine, really like the 21-5 at the minute just didn't know whether to get another or try the 21-5k ?

a really bad ass all around engine is the plus 21 block with p/s/r set #08536 installed this set has huge vertical transfer ports and a lowered , extremely large rear main intake (big power), but yes the 21-5k does give a little more fuel efficiency and a great powerband , even better with part #28011 turbo underhead
monty

Hi,

will a 21-5 piston liner and conrod fit straight into a 21-5k crankcase?

thanks

it will , but the diverters in the block make the fuel flow into the combustion chamber do some weird stuff

will a 21-7 piston/sleeve fit in a 21-5k block and if so how good will it run, thanks also did novarossi make a 21-7 and a 21-7b , not sure because i got the engine used

21-7 and 21-7b are pretty much the same thing , if you are going to replace the p/s/r with anything but the 21-5k set use the 821b p/s/r set , it works the best and you will gain a little performance .


the ports will not line up right and you will lose performance .

cool , i will just use a spare 21-5 case for my 21-7 p/s since i believe they are the same. also how can i tell the difference between a nova 28021/28011 head button used on a 21-7 vs a 28003/28002 head button used on the 21-5 , will the 2 styles interchange?? thanks

Just got the second gallon through the Nova 21-5K in the Mugen buggy. Running the Ofna 053 pipe with long header. 12t cb and 48t spur gear (short tight track)

Very pleased with this motor...smooth strong bottom and a very good top end.

2 clutch springs @ 1.1 and one spring @ 1.0

I was having a bad driving day so I ended up in a 10 minute B Main so I went for it...made the whole main with about 30 seconds of fuel in the lines at the end.

temps right at 220-225 rain or shine

idles for days!!

pulled it off Ebay for 230 delivered

I got one for sale..If you want one PM me..I DO NOT like this Mill!

the plus 21-5 is a first gen plus before they changed to the double thick top ring in hopes that the pinch will last longer with thicker material . there are the old style with a step on the underside of the button and then the new style which is deeper but uses the same amount of shims and has no step .

wondered why they changed that. that clears it up. Although I don't see a need for that. the original had crazy/long lasting pinch as it was.

i think the idea was to make em so they broke in faster but lasted just as long .

houston, with tko ceramic rear bearings, are you pulling the shield?

Rear bearings have no shields. If your bearing has them, take them off. Only front bearings have shields. Make sure you install them with the balls facing the back.

call me i need to see which bearings you have , or just send me picks , if they are the sloppy 14.5x26mm bearings , do not install if you are sponsored by jim , get my number from him .