Ruima bbk and stock exaust

Ricerider · Post by **Ricerider** » Mon Apr 25, 2011 6:11 pm

Got to take my first long ride today, drove thru town a few miles at 30mph, then hit the country and cruised at 45 for 1/2 mile before the dreaded loss of power and back tire locked up. Thought the motor was toast for sure, I let it cool for 15 minutes and decided to limp it back home after making the carb as rich as possible. Yeah I got lucky...

Anyways I jetted rich after installing the bbk, and jetted down untill it cleaned out at wot, so it aint lean...
I am thinking the stock exaust is way too small....

The bbk is a bolt on kit right? no milling needed??

Anyone else have probs with the bbk and stock exhaust?

01' sa50
51mm ruima bbk
120 main jet
pod filter
ruima var
9g rollers
9:1 gears
32:1 klotz r50 syn
Exhaust washer has been drilled out

evilone · Post by **evilone** » Mon Apr 25, 2011 7:00 pm

There are different thoughts about this but.....did you enlarge the boost port?

Ricerider · Post by **Ricerider** » Mon Apr 25, 2011 7:54 pm

No, are you talking about where the engine cases lead to the boost port, or the boost port in the cylinder itself?
It is not pushing all the exhaust out?

wiguy05 · Post by **wiguy05** » Mon Apr 25, 2011 8:12 pm

There isn't much of a problem running stock carb/exhaust with a 51mm kit.

What does the spark plug look like? Did you cut the boost port in the crankcase?

Sounds like a common case of someone who "bit off more than they could chew".

losthope · Post by **losthope** » Mon Apr 25, 2011 8:20 pm

what do you have the needle set at? Stock pilot jet and needle setting too lean for your setup just one of many things it could be.

evilone · Post by **evilone** » Mon Apr 25, 2011 8:24 pm

Ricerider wrote:No, are you talking about where the engine cases lead to the boost port, or the boost port in the cylinder itself?

Like wiguy said, the boost port in the crankcase.

Ricerider · Post by **Ricerider** » Mon Apr 25, 2011 8:27 pm

Looks like the 51mm ruima kit has the 18block boost port, I am so glad the "seller" let me know this.....

Wheelman-111 · Post by **Wheelman-111** » Mon Apr 25, 2011 11:15 pm

Greetings:

Some say they've had good luck flogging the Ruima 51s, despite bad tuning.
I have not. I fried one with a ministroke and all the intake and exhaust goodies. Ran over 70, just not for long.
I don't know why, for sure, but suspect the thin cylinder wall is part of the issue.
Maybe it's the metal, or poor dimensional precision. Maybe the 80cc+ heat output exceeds what Honda-san's fan can control.
My Char-Mo 50mm did fine, but I wouldn't buy a 51 or 52 - egads! Maybe if you get a "good" one? But how to tell?

Ricerider · Post by **Ricerider** » Mon Apr 25, 2011 11:46 pm

Really considering scrapping this ruima and selling the extra sa50 motor I have to fund the polini corsa, its only a 72cc vs 85 with the ruima but at least it will run. what speeds can I expect with the polini on stock carb with 9:1 gears? thinking about the hand ported polini corsa.

I would never run the ruima wot for more then 15 secs, but is it safe to hold the polini wide open?

If this is an issue there should be a sticky so people dont waste there money on the ruima 51mm

wiguy05 · Post by **wiguy05** » Tue Apr 26, 2011 12:04 am

Ricerider wrote:Looks like the 51mm ruima kit has the 18block boost port, I am so glad the "seller" let me know this.....

You didn't notice when you laid the base gasket down that the port was twice the size? Plus, there are dozens of threads on this forum that thoroughly discuss this topic.

I would suggest doing a thorough search before attempting major mods (which a BBK would be).

wiguy05 · Post by **wiguy05** » Tue Apr 26, 2011 12:07 am

Ricerider wrote: I would never run the ruima wot for more then 15 secs, but is it safe to hold the polini wide open?

If this is an issue there should be a sticky so people dont waste there money on the ruima 51mm

There is nothing wrong with the Ruima 51mm bore, or any of their others for that matter. Proper installation, break-in and jetting is required for ANY bore kit.

Bear45-70 · Post by **Bear45-70** » Tue Apr 26, 2011 12:49 am

Sounds to me as if it is jetted too lean and seized. Since you have not done a compression check, whether it was a soft seize or not is still unknown.

bakaracer · Post by **bakaracer** » Tue Apr 26, 2011 1:23 am

you need to run an extra head gasket to lower the compression and you need to run the airbox if using the stock carb due to the small pilot jet. running it with a pod filter, every time you drop down to 1/2 throttle or below, your way to lean so it heats up even more. that with the high compression ratio and low octane gas,equals seize.

Ricerider · Post by **Ricerider** » Tue Apr 26, 2011 1:39 am

Ok so how about the 72cc polini with stock carb and airbox on 93 pump gas with one head gasket, would I be ok then?
Thanks for all the help guys, thougt I knew my s*** but I dont

Trafficjamz · Post by **Trafficjamz** » Tue Apr 26, 2011 2:09 am

Ricerider wrote:Ok so how about the 72cc polini with stock carb and airbox on 93 pump gas with one head gasket, would I be ok then?
Thanks for all the help guys, thougt I knew my s*** but I dont

The polini has a o-ring head gasket....can't stack 'em.

The polini kits are ready to bolt on a go.

They come with all gaskets, piston, jug, rings, wrist pin,wrist pin bearings, wrist pin clips, CF reeds, a new jet,a spark plug, and polini stickers

.

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Ruima bbk and stock exaust

Ruima bbk and stock exaust

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