Was thinking of getting a head for my ski but wanted to know what that did to the reiability factor. All I do is rec riding so I dont need an elaborate head, just something to get more comp. Will I lose reliability in the long run if I go with higher comp.? If not which head other than a stock milled head. Thanks

I had Group K modify a stock head for me with their "swift kit" and it was the one mod that I did that had the most noticeable gains. If you increase the compression then the engine will wear faster than stock, but its well worth it. Having a stock head modded always runs a risk of even a reputiable shop having a bad day, but if you want to remain running pump gas (89+ octane) then the modded stock head is a great option. If you want to go with higher compression and run premix gas (100+ octane) then get the girdled head from RIVA. I hear ADA makes a good head too.
I don't know if their is any local shops in your area, what I did was buy a new stock head and had it sent to Group K for modification and then they sent it to me. That kept me going until the new head arrived.

Thanks Rich, Thats what I was thinking too. Its always nice having someone clarify that for you.
Shane where's that head you sent out for me?

Would I be better off going with a stock milled head or say a R&D red head or Riva. Something of that sort.

I mill heads all the time for customers and never have problems...... with yamaha's I feel it does not cut their longevity as much as some of the competitors. BUt I run around 190 psi on all my motors and still oil inject most!! Have VERY few problems......

Normally...and I state normally cause I have never had any problems with higher compression motors either, but the higher the compression, the lower the reliability of the engine....so I've heard. I've been running GP's, SXi Pro's, and Superjet's with compression in the 180 range and havent had any problems. I've always run R&D heads and the only thing I have had to do is change the orings around the domes. Just dont go over 200, or you will have to run Race Gas.
Good Luck, Happy Riding

Thanks guys, was thinking around 145psi. I guess I should just stay with a stock milled head?

only advise i can give to you is that if it is for a 97-99 gp1200 don't go over 150psi or else you have to run race gas(104+ octane) - from personal experiance and spending lots of money. Groupk says the stock head supplys enough cooling, so unless you plan on being able to change you compression(ie. removable -interchangable domes), for your situation the stock head modded by groupk or another person sounds good/ most bang for your buck. riva heads are expensive - especially the girdled ones. one more point... make sure whoever does your head work knows exactly how to tune your ski after that mod is done. good luck.

I have a 99gp1200 with riva head cdi and other parts running 41cc domes 150psi can i run 38cc domes 170psi on 98octain fuel

njrealtor55 where did you get the paint codes also anyone know where i can gt a cdi for a 99 gp1200

i have one of the last cdis that riva had for the older gps , its the blue plastic not the purple and has only been used about an hour . its still in the original box with the original instructions and sticker 200 firm .

Stock milled head will work. But there are advantages and disadvantages. On a mill job you are relying on someone and hopefully they are having a good day, you cannot change dome sizes if you go to higher altitudes (must have here, races are from sea level to 3500 feet) or want to race closed course or local endurance races where you may want to temporarily bump up and run race gas mix, you will have to shim the exhaust brackets that mount from the head to the studs off of the pipe, if you sieze a piston and screw up one cylinder you will have to buy a new head base section and gasket, plus have head milled again, more downtime to send out and get back, would need to verify squish and compression on each cylinder compared to what was promised, etc......

Most aftermarket heads have interchangable domes for racing, climate or motor work issues, extra cooling capabilities, better heat disapation, they look cool, and can return some investment if you decide to sell the boat by putting your nice stocker back on and selling the aftermarket, the domes are cut by computer controlled machines, squish can be pre-determined by brand and easily verified, etc.... Cost is 100-150 for a mill job vs. 300-600 for aftermarkets depending on brand. A milled head could end up costing close to the same as an aftermarket if any unforseen problems happen due to engine failure.

To me if your budget allows, aftermarket all the way and either R&D/Riva or ADA rec heads. There is pro and cons between these as well etc.....Stay away from the triple pipe heads unless of course you have or plan on triples.

Just my 2 cents!!!!!

When you say stay away from the tripple piped heads doesthat mean the heads like the Riva pro-series billet head?

pro1gpr email me @ jetskiier800@aol.com im very interested in that cdi any one know the paint code for tha riva blue well time to get out the snow shovel

Our Pro-Series Billet Heads aren't specifically for triple pipe applications. We strongly recommend these for high compression applications such as Limited and Superstocks, but we also sell domes to fit these heads for lower compression applications such as our Stage I~III Kits (150psi) and RPM Kits.

The only application our Pro-Series Billet Heads will be required for is our GP1200R/XLT1200 Big Bore Kits. This is due to the larger displacement and increased torque.

[ 01-19-2002: Message edited by: RIVA CREW ]

Thanks Riva Crew! Thats all I needed to hear.

The Miller racing head that is resold under a few different names does not work well with the stock pipe due to bracket issues. To much vibration. It is specifically designed for triple pipe boats and allows dome changes in minutes. It may work ok with a S2 but never tried it.

Riva crew does the Pro Series head work with stock exhaust? If so, what type of brackets do you use?

Brett,
Yes. The two stock brackets that are mounted to the pipe via the M8 stud mount to the SS bosses included with our kit. The center and rear head cap mounting locations are utilized for single pipe applications and the rear only for triples.

Riva crew, do you use the front bracket on number one cylinder?

Yes. We include two aluminum spacers and two longer bolts to mount the bracket (plate) to the cylinder head.

quote:

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Originally posted by RIVA CREW:
the rear only for triples.

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This should have read "the rear only for FPP triples. The Speedwerx triples use the front to mount their center pipe".