Just bought a 2008 summit 800r

[Kao30]

I just bought a 2008 summit 800r bored out to an 890. The guy I got it from said it runs on high octane race fuel. Was wondering if I can get by running 91 or 94 octane in her or stay with straight race fuel. And if so what octane you recommend?

 

[lilduke]

Whats the compression? Whos BB kit? Never seen a 890 before

 

[Kao30]

All I know it has a big bore kit and that's what buddy told me. Other than that I'm not sure. It has a air fule ratio gage.

 

[slededjr]

890? interesting. is there any markings or name on the head, or is it a cheater head (stock head modified)? If no markings, try to find out from the guy who's kit it is.

 

[Kao30]

The guy I got it from his brother is the one that owned it and is back in Newfoundland. Ok I'll check the heads I know theirs markings. Pretty much every thing on the sled is after market

 

[slededjr]

yeah, see what it says. post on here or send a pm. either works.

 

[Kao30]

I'm thanks guys for the help. I just don't want to blow it up like my last one lol

 

[Kao30]

Has torque line headers

 

[HotShotHarry]

Thats RKT.s head. Its probably an 860.

 

[Kao30]

To be honest I have no idea just going buy what I was told when I bought it.

 

[neilsleder]

To be a hundred percent sure you could pull the heads and the domes will have the compression stamped in them.


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[MADMAN]

U bought a sled blind? Hope it turns out to be a good machine for ya. And hope u paid a decent price.

 

[duck]

Its probably an 860. Don't think you can go much bigger in the bore, or else someone (aftermarket mod shop) would have done it already and it would be more popular.

 

[kovs]

If he said to run on race fuel I would stick with that who knows what compression domes he has in it.
I'm going to venture to guess that you are going to have problems with it.


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[neilsleder]

Its probably an 860. Don't think you can go much bigger in the bore, or else someone (aftermarket mod shop) would have done it already and it would be more popular.

There are 880, 872 bob for those motors.


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[pfi572]

It's not a 890 as no pistons.
Probably a 880 SHR with RKT head (BJ uses RKT )
Or like has said a 860

 

[Modman]

Its probably an 860. Don't think you can go much bigger in the bore, or else someone (aftermarket mod shop) would have done it already and it would be more popular.

You can go 880, that is the biggest "bore" they make. Its the Monoblock that causes issues above this displacement because you cannot move things around in the block (water jackets etc) and would require work to ports etc. Many problems with the 880, the walls are pretty thin at the 880 size, transfer ports and intake ports lose a lot of support. Guys are making them work but when you run it hard you will see some distortion. Trygstad had a prototype 890, required offset boring of the monoblock etc.

To the original poster - Don't start cheaping out on fuel. If you wanna run pump at the elevation its set for, get different heads for it but don't run cheap fuel in it. Depending on who's BB kit is in it, if its forged pistons the locating pin can come loose from detonation (from using too low of an octane) and then you will be replacing motor parts. Best thing you can do is run what fuel needs to run in it, otherwise you are asking for trouble. Soooooo many motor failures related to guys doing this its unthinkable. 2 biggest causes of detonation related failures in motors IMO - Its either big bores with high compression or turbos with boost controllers set too high for the octane they are running - both failure scenarios where peeps don't give the extra octane for the motor and result in engine failure.