14.8 RKT head question?

[Chazmanian]

14.8 RKT head question?

09' 800R summit. SLP intake. HPS Can.

I unload at 8500 and will be riding in the 9-11K range.

I have a sweet looking new 14.8 RKT head.

Nice looking piece of work by the RKT crew. The domes are radically different from the stockers for sure!

Anyhow....Is this 14.8 gonna Deto at 8500 on 91 pump gas?

I did a search and just couldnt quite get a straight to the point answer. It seemed some guys were having no issues...Some were...

One guy siezed his at WFO at 6500....

We have 91 Octane E10 gas in Colorado. I can bump the octane if I must as I keep lots of Toluene around the garage for my ping master high compression Harley that literally wont run without it.....

I would like to not be adding expensive Toluene to every tankfull and can probably exchange the head if needed as its new and unused....

8500-11,000 14.8 with 450 mains and the shims sound safe on 91???

Curious as to what elevation some of yens are running the 14.8 head at as well and with what jetting.

Thanks Gents!

 

[PJ-Hunter]

I was speaking with Donovan today regarding the 14:6 head I had last year and he said that was a tad too tight for the "high quality" gasoline we have here and I ride 9000' and up. That head detonated last season.

 

[Chazmanian]

Thats my fear...I thought I had a 14.6

Ummmm Not.

Its a 14.8.

I wasnt so worried about the 14.6 but when I saw 14.8 scribed on the domes I thought were 14.6?

I started wondering.

 

[PJ-Hunter]

Try calling Kelsey and see if he'll trade ya out. Be nice and explain that the fuel quality won't allow that tight of a head.

 

[Chazmanian]

Didnt buy it from Kelsey....Bought it from another source.

Its gonna need swapped out eh?

Damn.

 

[Backcountrypro]

Go the safe route....go 14:1.

 

[Adrenalin]

while were on the subject , not meaning to hijack your thread but whats a safe number for 1k-3500ish

and whats the stock head ? 12.5 ?

 

[Chazmanian]

while were on the subject , not meaning to hijack your thread but whats a safe number for 1k-3500ish

and whats the stock head ? 12.5 ?

I wanna say the stocker is 12.25-1

 

[BIG JOHN]

Chuck- the difference from 14.6 to 14.8 is almost unmeasurable with a buret...14.6-14.7-14.8 are basically the same compression...

AGAIN- RKT has used this comp ratio for 7000'-9000' for YEARS...I use it in my sled...

You ride 8500+...put it in and ride...if anything just bump 1 jet size from spec...BJ

 

[Chazmanian]

Chuck- the difference from 14.6 to 14.8 is almost unmeasurable with a buret...14.6-14.7-14.8 are basically the same compression...

AGAIN- RKT has used this comp ratio for 7000'-9000' for YEARS...I use it in my sled...

You ride 8500+...put it in and ride...if anything just bump 1 jet size from spec...BJ

I'm starting with a set 450's with shims....

When you say bump one jet size from spec would that be up a size from spec being 450's when not having my ECM recurved?

So 460's?

I see Kelsey is running 430's? Yowsa.

 

[BIG JOHN]

450's is where I start all my customers...I know Kelsey has gone down to 430...so 450's is a safe start point...at your elevation this is a 91-92 pump gas head...460's if your worried about fuel quality...if plugs are dark and you have no issies than drop back to 450's...BJ

 

[Chazmanian]

Thanks John.

I'm gonna mix up my crazy brew just for piece of mind...Thinking I'll do a 90% Premium pump gas with 10% Toluene and an ounce or two of MMV per tank.

That would yield me 93.5 Octane at an additional cost of $5-6 bucks per tank not a biggie as we dont really trail ride and I wont be laying down any 150 mile days anyway......

I'll plug chop on the 450 main's and see how they look before rejetting to a 460. Hate to give away any gains via skeerdy cat uber rich jetting.

Thanks again John! If it pops I'll be calling ya!!