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Exhaust Packing And Rivet Drill Out


ktmsprocket
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Guys...Has anybody drilled the rivets and then re-packed the muffler? I'm just about to do it, but was wondering if you get any surprises!!!!

I was going to drill the rivets and replace with 10G stainless self tappers....

OK?

No suprise what so ever, done my grandsons 50cc, the old packing whas just soaked in oil thats all, seemed a bit quieter after!

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Thanks Guys. I didn;t think there would be an issue...but you never can tell!!! I reckon it'll drop a kilo in weight too....the silencer is very heavy...I reckon its full of oil and water!!!!

I have a follow-up question too....the rubber seal where the silencer slips on the exhaust pipe is not tight and is not a very clever design. Do you guys just buy new ones....allow the oil to drip and ignore it, or have some other neat way of making the seal???

Edited by KTMSprocket
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Hiya, my daughter ran a Rev 50, superb little bike. I changed the exhaust packing every 6 weeks which kept the bike running brilliantly, they don`t burn the fuel efficiently and leave a lot of oil in the system. I drilled out the rivets and then tapped the holes 6mm and used button head allen bolts, this made it a simply task every time. Regarding the seal just clean the pipe well and use clear silicone it works a treat. Another handy hint you may want to try is using an octane booster in the fuel, as the riders of these little machines tend to be soft on the throttle the bikes have a tendency to soot the plugs up, with the booster added at a 2% mix (20ml/1ltr) it makes the engine run much cleaner.

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How61...Our KTM Minis have much the same exhaust system and we change the packing very regularly (its easy to do) with Rockwool (very very cheap).

I'm glad you mentioned about tapping the holes 6mm. I will do that instead of the self tappers (I wasn't sure how much metal I would find when I opened it up).

Not sure about the silicon though, I'd prefer a proper fit but I suspect that will be pretty tough to do unless I made up a 'clamp or pinch' arrangement. Hmmmm...??

We run 40:1 mix in the KTMs, but they are screaming and get very hot, hence most stuff is burnt unless the engine isn't tuned right. I'm new to these 2T Trials bikes and as they don't get hot and aren't ringed out....I would think that I'd run:

Motul 600T (or 800T) at 100:1 ?

Maybe lean out the carb at the fuel screw?

Leaner pilot jet?

Leaner main jet?

Slightly higher idle?

Any comments?

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Hi J

There are a few mods you can do to stop the silencer oiling so much. Here's what we did with our 2005

Go hotter in the spark plug. We used a NGK B8ES mostly but sometimes went with a 7 in cooler weather.

Open up the airbox lid so it breathes a bit better - pic below.

Leaned the needle position. Clip was in position two from the top.

Play with the mixture screw once you've changed the needle and opened the airbox lid. I ran the idle a little higher to help stop stalls.

I don't want to start a fuel oil debate, but as soon as I stopped using Motul 800 oil (first in Shell optimax and then in BP Ultimate 98) I found less jetting hassles and much less oiling issues. We now use BP Ultimate with BelRay H1R at about 80:1 (62ml per 5 litres)

The 50 ran cleanly and with a near perfect plug with the above settings (slightly sooty on one side sometimes) and I had to replace the silencer packing much less after that. Even so, every so often I gave it to the older boy who gave it two or three laps around the MX track at higher revs.

Oh I ended up squeezing on a second o-ring to seal the silencer to the pipe, sometimes with a smear of that blue silicon.

Got our 2006 model Rev 50 yesterday. It seems to idle much more smoothly and is much more responsive at low revs. I did the aibox mod but everything else is stock. We are running-in at 70:1 with the above fuel/oil. It runs very smokey.

Hope this helps

post-957-1137052885.jpg

post-957-1137052955.jpg

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How61....

I did as you suggested....worked a treat. Drilled out the rivets gently, tapped the holes in the steel endcaps 6mm, drilled the existing holes in the aluminium casing a little larger (6.5mm) to make it easier to line up the holes.

Finished the job with stainless spring washers and hex cap heads.

The packing that came out was dripping with yuch like u wouldn't believe.

Cheers

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