SX/SXi/SXi Pro New to the Ski world...need some help w/ 300sx!

[WFO Speedracer]

lol


I didn't think you were like that, terry.

You are correct its all in Steves warped imagination :ugh2:

 

[WFO Speedracer]

WFO, in that box of carbs you have, is there maybe one or two i could put together to get this ski running?
Thanks

I have given you the best advice I could possibly give you which was to ditch the BN for an SBN,not only that I tested SEVERAL and found one that would hook up to your stock cables and work flawlessly without rejetting,changing throttle drums,eliminating the choke plate or doing any needless tinkering,Now I could surely find you a BN carb that might work after rebuilding it but what would you have? The SBN carbs work better,need no tinkering,they are completely rebuildable,and REJETTABLE,THEY ALSO INCREASE HP AND FUEL MILEAGE.The BN carbs require constant tinkering are not rejettable ,why would you not replace the BN with a SBN?:ugh2:

 

[the WaTeRhAwK]

gimmee the carbs.....lol

 

[WFO Speedracer]

gimmee the carbs.....lol

I will get them boxed up and see what I can do.ancake:

 

[neattouch648]

ok! got it! sorry i got a bit confused....so i want an SBN carb....:biggthumpup:

 

[WFO Speedracer]

ok! got it! sorry i got a bit confused....so i want an SBN carb....:biggthumpup:

Yes off of a 91 WR500!:brap:

 

[WFO Speedracer]

BN carbs also called round body carbs were the first carbs used on watercraft,they came in 34,38 and 44mm versions they had fixed jet sizes so if you wanted bigger jets you drilled out the fixed jet,there was no going back after you did this.So thats what everybody ran till the SBN or super BN also called square body carbs came out in 1991.In 1991 every mfg switched to SBN carbs across the board,they were much simpler ,had fewer parts and removable jets.

 

[sflsurfrider]

BN carbs also called round body carbs were the first carbs used on watercraft,they came in 34,38 and 44mm versions they had fixed jet sizes so if you wanted bigger jets you drilled out the fixed jet,there was no going back after you did this.So thats what everybody ran till the SBN or super BN also called square body carbs came out in 1991.In 1991 every mfg switched to SBN carbs across the board,they were much simpler ,had fewer parts and removable jets.

thats not true. brazing over the 'plates' and redrilling was a very common practice for tuning the BNs on modified skis.

 

[WFO Speedracer]

thats not true. brazing over the 'plates' and redrilling was a very common practice for tuning the BNs on modified skis.

Yes so was cutting the tops off and installing angular discharge booster venturis such as the Jack Green racing carbs,adding power valves such as the Bad bones conversions etc etc,I will rephrase that for you,there was no easy way to go back.:slap:

 

[neattouch648]

well....i just ran into some more trouble....haha

I gave the ski back to the guy i bought it from so he could try and figure it out. He gave it back to me today and said he had no idea but agreed to help me pay the repair bill....I know you said it was the carb so i'm still looking for one...if u can help me find one that would be awesome but anyway! it won't start at all anymore so he checked compression and there is NONE haha... one problem that i found was one of the head bolts is not tight....now in the auto world, this can cause loss of compression, even if only one bolt is loose. Could this be the case here too? A head bolt was loose and that ruined the gasket and thats where i'm loosing compression?

Thanks....

 

[WFO Speedracer]

Yes highly possible,I had a problem with some clogged cooling lines on a 300sx I got last year from a member here,it blew out the head gasket before I got all of the lines unclogged,no compression on that one also.What I did was take a new 650 metal gasket and mark the cooling holes on it,I then drilled out the cooling holes in the proper locations and cut out the gasket with some heavy duty scissors.What I ended up with was a metal head gasket for a 300sx,this increased the compression and is more resistant to blowing out,so far it runs perfectly with this modified gasket.:bigok:

 

[neattouch648]

Well, its not the gasket, the gasket looks fine, when i push on the piston, (back and forth) it actually moves maybe 1/32 of an inch or even a bit more...i know for a fact on my truck engines that should NOT be allowed. is the same true for the jet ski?

 

[WFO Speedracer]

The piston is supposed to rock in the bore at the top,clearance of the piston is set at the bottom or close to the bottom of the skirt.Here is why,the piston crown is subjected to intense heat,as the piston crown heats up it expands,the piston is cam ground which means its tapered ,smaller at the top ,bigger at the bottom,since the piston crown is subjected to more heat it expands more taking up the additional clearance at the top of the piston.Now what happens when a piston seizes is that the piston actually becomes bigger than the bore it is traveling in,metal to metal is made and aluminum actually sticks to the cylinder walls=not good and it means time to overbore it to the next available oversize and install an oversize piston.