Posts
120
Joined
10/10/2016
Location
GB
Edited Date/Time
6/20/2019 7:35am
just want some opinions on my cylinder i bought this bike a while ago and told it was ported im not a 100% what im looking at
it does look like its had some grinding done so i thought i would get some pics while i ts apart see what anyone thinks
it does look like its had some grinding done so i thought i would get some pics while i ts apart see what anyone thinks
The Shop
had me a bit concerned when it got called rough as long as it useable ill leave it as is for now maybe send to someone in the future
Thanks
Cause poor flow characteristics till the engine can flow enough fuel and air to negate the obstruction of flow, most stock port heights are aggressive enough for mortals, if you want to make more power all over, smooth out every single transition you can so there is nothing that can impeed airflow, ports don't impeed air flow, mismatches in the cases and casting flaws do
do you know what sort of effect raising the exhaust port will have where does it move the power too any info would be appreciated
ill measure the exhaust port height tomorrow
i also tried it with a tape measure and got about 28
Pit Row
You don't have any good pics of the roof and powervalve of the exhaust port. Does it look to be milled/sanded? That will give you a good indication too.
its not too bad to ride but compared to the kx its completely different
my measurements may not be the most acurate i probably wont dig too deep into whats been done this time around just want to get it up and running now
Been notorious for bottom end delivery, I will say my 99 was an acception, I bet that engine would blow the doors off a new yz125, it was impressive, it had a way better mapping setup though, pwk longbody, with a powerjet, it was a sweeet powerband, and the pro circuit exhaust was explosive, bottom to top, it pulled effortlessly, I owned that one recently, and when I was 16 I owned a 2000 rm125, and i can for sure remember it had zero low end, allllll top, and the pc exhaust was the same for it as well, explosive, such a good setup.
Now for your engine, I can't say for sure, but judging by the looks of what's been done, it's merely been a port clean, and possible matching the cylinder to the cases, just by looking at the degree of grinding, and blending that's been done, there hasn't been any port height alterations that I can see. If you get a couple sets of chop sticks, you can wrap any grit of emery cloth (sand paper) you want around it, 80-120 grit works good, and then just sand it out by hand without buying a dremel, may take longer but it still
Achieves the same results, and it will get into the little corners of the port sides easily. I use this method to finish all my cylinders by hand after any dremel work, just seems to come out more consistent and cleaner, Iv gotten a few cylinders back from porting work that's been done, and ended up finishing them by hand, to smooth out the quick work that had been done. All in all though, nothing bad has been done, old school method was knife edge the port bridge, but it's been proven that a rounded surface is better for splitting passing air, so everything looks like it's at a great starting point if you want to experiment and smooth out your porting surfaces. If I get onto porting my 125 sx cylinder in the next bit I'll post some before/after pictures too, I don't alter port heights myself, mainly due to the fact I don't have a 90 degree dremel head small enough, but I usually find you can uncork a lot of airflow just by smoothing everything out
i did email a company here in the uk but they didn't seem keen as someone else has done work to it which is fair enough i suppose
i will try gibbs at a later date
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