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RT180 Power Reeds

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#1
I'm not upset with the overall performance of my 93' RT180, I'm just looking to give it a little wakeup. It can be sluggish at times and I just want to get it a little peppier than stock.

There are NO aftermarket parts for the RT180 other than power-reeds and I think this may be all I really need.

I'm currently ordering from Dennis Kirk a small parts list.

2 new tubes
new sprockets
new chain
new airfilter
and new brake shoes (rear)

The power reeds they have are only 30 bucks and I can easilly swing them. I just want to know what sort of gains can be expected from a reed-only upgrade, also will I have to rejet, or will my mix not be affected?

Thanks for the help.

Dan
 

RM_guy

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#2
You should really take a closer look at the blockage in the exhaust port. Removing it and re-jetting makes a big difference. I wish I had taken pictures of mine to see if it's the same as your bike.
 
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#3
I took the tube off a week ago to clean behind it and I didn't notice a specific blockage or anything. Is the blockage in the downtube or in the cylinder? Can I remove it with pliers or is this a dremel-job?

I do have an FMF can for a FMF Fatty built for a 88 KDM200 that fits almost perfectly in the stock position.

I'd like to do the reeds, exhaust restrictor (if you can kinda guide me to where it is) and the silencer... Also, will ANY mikuni jets work in the carb, or are they model specific? (How many jet sizes did you have to jump up to get it to run well?)

Thanks RM.

Dan
 

RM_guy

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#4
The blockage is in the port in the cylinder and you'll need to grind it out. If I remember, it ran with out re-jetting but was rich. You should be able to get jets from a local dealer.

The silencer probably won't give you much performace gain and it might be louder.

I'd go ahead and change the reeds.
 
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#5
Is the blockage part of the cylinder, or is it a piece that was grafted in by the manufacturer?

Also, did you change the exhaust port geometry at all, or simply the blockage around it. I know that if you go to far into the cylinder (like enough to change the shape of the port in the cylinder) you can really mess up the exhaust timing and completely mess up the motor (I've done this before on a 50cc moped... not fun.)

However, if it's a clear-cut blockage, it shouldn't be a problem.

By rich you're saying there wasn't enough air to compensate for the fuel right? Thus I'd need a smaller jet than stock?

Thanks again for all the imput so far!

Dan
 

RM_guy

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#6
It's actually in the alum casting. I didn't change the exhaust port dimensions in the cylinder at all. It could probaly stand for some tweaking but if you don't know what you are doing it can spell trouble, as you seem to already know ;)

Yes, I had to lean it out.
 
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#7
Thanks RM_Guy,

How exactly did you remove it? Dremel or a drill?

I know what I'm doing as far as 50-70cc 2-strokes... but that's mainly with German mopeds and scooters.. lol. Actually, the Yamaha shouldn't be too different, but I'm not looking to mess with timing, just the blockage.

Also.. would any Minkuni Jets work? or are they specific to the model of carb?

Dan
 

RM_guy

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#8
I used a dremel to grind it out. Just open it up so the path from the port to where the pipe hooks up is all open and smooth. Be careful not to grind through the wall. If you do it can be welded back up.

Any Minkuni jet should work. Find out what you have already in the carb and get a few in each direction.
 
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#9
Thanks a lot! I'll take a look this weekend and see what I can do. Did you have to remove the cylinder or can you do it on the bike?

Dan

P.S. I've checked Dennis Kirk and did a google search, I can't seem to find exactly what I'm looking for for jets. Should I go to a dealer, or is there a better site that I'm just not finding?
 
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#10
I would assume it has a cast iron sleeve, if so to obtain more power you could always bore it to the highest over bore size (usually .60 or .80) And at that time would give you the ability to do the mod that RM_guy did. I doubt that would cost more than 200.00 and would make a noticeable power increase. Power reeds will probably make it more resposive throughout the rpm range, I doubt it will give you any noticeable power increase.
 
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#11
I'm pretty sure the entire cylinder is cast-iron. It's a different compound than the head, that's for sure.

Dan
 

RM_guy

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#13
It's a cast iron sleeve and you could bore it out for more power but you will run out of options if you have to do a bore due to wear. I'd leave it stock.

You will need to romove the cylinder to open up the exhaust. There will be lots of alum debri.

If you have a good dealer I'd go to them and explain what you need.
 
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#14
Cool, like I said, I'll check it out this weekend and decide what I'm going to do. The power-reeds are a definate... also, I think the stock rear sprocket is a 51, and my bike is a 6 speed... it wouldn't hurt to up the teeth on the rear sprocket a little would it? Maybe by one or two? Give it a little more grunt in the low-end?

Dan
 

RM_guy

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#15
A bigger rear sprocket is the cheapest was to get lots of low end grunt. You will have to shift more and you'll loose some top speed but...;)