Author Topic: PE 250/RM 250 top end swap  (Read 5862 times)

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Offline Gonzo

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PE 250/RM 250 top end swap
« on: June 04, 2015, 04:40:55 pm »
Hi all, my PE 250T is on it's last rebore so I'm looking for a replacement barrel to get rebored and swap out when the time comes. I see a couple of 1980 RM 250 top ends on the old evil bay. They look identical but from what I can gather the part numbers are different. Does anyone know if the top ends are interchangeable between the PE and the RM 250 of similar vintage? Also I want to strip the paint from the barrel and head before re boring. What's the best method? Blasting? Chemicals? Or what? Thanks in advance. Here's the PE as she stands. Runs great. Suspension not so great. Brakes also not so great but I do love this bike!

Offline sleepy

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Re: PE 250/RM 250 top end swap
« Reply #1 on: June 04, 2015, 05:16:09 pm »
You are counting the aftermarket OS pistons up to 2mm over?
Don't know about the differences in the 250 but would assume that the PE would be milder in the porting.
It is quite possible to sleeve your barrel back to stock and have it work as well as original.
Best to use paint stripper and then bead blast to re-paint.

Offline Lozza

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Re: PE 250/RM 250 top end swap
« Reply #2 on: June 04, 2015, 06:35:54 pm »
Plate the cylinder with nicasil to a size readily available piston. Bore and Stroke are the same between RM and PE a >90% chance it will fit compare a base gasket
Jesus only loves two strokes

Offline Gonzo

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Re: PE 250/RM 250 top end swap
« Reply #3 on: June 04, 2015, 08:19:29 pm »
Thanks guys, yes the part numbers are the same for base gaskets for 1980 PE and RM Lozza. Could be a go. But the piston pin is a different number between the 2 so maybe use PE piston in RM barrel but then porting probably won't match. I'll check out costs for resleeving and plating, see if they're an option. Porting, that'll be the difference for sure sleepy. I like the broad power range of the PE. Very easy to ride. I'd guess the RM would be more peaky.

Offline fred99999au

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Re: PE 250/RM 250 top end swap
« Reply #4 on: June 04, 2015, 08:38:43 pm »
Who will do a good job of nicasil plating an iron bore Lozza? Assuming you are meaning to do it to an iron sleeve.

Offline GMC

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Re: PE 250/RM 250 top end swap
« Reply #5 on: June 04, 2015, 08:41:30 pm »
I had some RM & PE stuff many years back and I remember comparing the 2 barrels.
I think the RM was a C2 and the PE an alloy tank model
Anyway the barrel ports were identical except the RM exhaust port was approx 2mm higher

Also keep in mind that sometimes the PE range was a year behind in development to the RM range so you may need a barrel from an RM that is a year older, some of the Suzuki guys may know better which models are similar

Plating the barrel will be a similar cost to resleeving.
I think if you intend to keep it you should consider a resleeve as most secondhand barrels will be close to the use by date as well
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Offline MaxPower

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Re: PE 250/RM 250 top end swap
« Reply #6 on: June 04, 2015, 09:51:37 pm »
That thing looks to be in great condition. Doesn't look like it has enough time on it to be out bores. You still haven have the stock shocks.

oldfart

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Re: PE 250/RM 250 top end swap
« Reply #7 on: June 04, 2015, 09:52:54 pm »
Pe 250 and Rm 250 T/ X are the same .... difference is Pe has rubber grommets on fins  and Rm non .
I have been thru this before many moons ago on another post showing pics and measuring ports.
 

note the notches in Pe barrel to take rubber
« Last Edit: June 04, 2015, 10:00:58 pm by oldfart »

Offline sleepy

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Re: PE 250/RM 250 top end swap
« Reply #8 on: June 04, 2015, 10:12:24 pm »
I was going to tell you that I couldn't find a listing on PE250 sleeves but LA Sleeves do a RM250X sleeve. May not be localy available but sure beats making a sleeve from scatch. Going back to stock will give you another 35 years or so.

Offline Lozza

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Re: PE 250/RM 250 top end swap
« Reply #9 on: June 04, 2015, 10:24:09 pm »
Who will do a good job of nicasil plating an iron bore Lozza? Assuming you are meaning to do it to an iron sleeve.

Millenium in the US or NZ Cylinders in.......New Zealand. Grant in NZ said the most they have built up a bore is 0.8mm so they took the bore size back 1.5mm after honing. Plating lets you take advantage of those super cheap original bore, first and second oversize pistons
Jesus only loves two strokes

Offline Gonzo

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Re: PE 250/RM 250 top end swap
« Reply #10 on: June 06, 2015, 04:58:38 pm »
Ok so, resleeving looks like the best way ahead but I can't find a listing anywhere for a suitable sleeve. LA sleeves don't seem to list one for an RM 250 older than 1989. Am I missing something sleepy? And if I go for an RM sleeve, I'll end up with RM porting, right? may have to get one made, sounds like an expensive operation. Can anyone recommend a good engineer who does resleeving or makes sleeves. Someone I can call and discuss my options. I'm in Fitzroy Crossing, WA , I'm going to have to send it to someone to have the job done anyway so anywhere in Australia is ok by me. Thanks for all the info guys. Great forum!
No standard shocks Maxpower. And overall condition is pretty good now.  There were a few parts missing or damaged when I got it. Wheels came from eBay in the states. Some parts from UK, Holland, and here in Auz, all over the place really. The plastics are new except the tank and I had the head off. It had already been rebored with new piston and the bore is 69mm. As far as I know, that's the last oversize for PE.

Offline Gonzo

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Re: PE 250/RM 250 top end swap
« Reply #11 on: June 06, 2015, 05:02:20 pm »
Oh yeh, GMC, I really want one of your exhausts for my PE. They look the business! Would the RM one fit and work well?