Ssr xf250 enduro, big bore to 300cc.

Hello everyone. I am new to the forum. But I decided to join to add a write up and pics to help anyone who would like to accomplish the same as I have done. I purchased an xf250 SSR dual sport about a year ago. I have put 5k miles on it in that time. I love it and it is a very fun bike to ride around to work. I see approx 75 to 80 mpg on a regular basis. Only issue I have had is a leaking head gasket, leaks oil slowly over time. Not too bad just the occational annoying drip on the exhaust.

And to the point, while hunting around I found a big bore kit for a gn250 from China. Making the gn a 300cc. While doing as much research as I could, found nobody has accomplished the task of trying to fit that big bore to the SSR 250 which is basically a Suzuki tu250. Only reading on a write up that it was the same engine bolt pattern. For the cylinder sleeve. So I decided to take on the task of ordering this kit and seeing if it would be possible to adapt it to my 250. Also the kit comes with all gaskets so it would solve my headgasket leak problem.

I will post some pics of my finished product and the link to the bore kit I purchased. And do an expkaination of the things that worked perfectly and the parts that screwed me but fortunately I was able to solve and now have a running SSR xf300.

Before I go into insane detail and go crazy cause I'm a bit ocd I wanted to see If anyone would be interested in this write up before I waste my time. Or if anyone is thinking of doing the same thing.

You should write it all up, who knows if there are any SSR 250 owners that may do the same? Most of these are relatively new, probably too new for most of them to even consider doing what you did, but as time goes on that may change and your thread may become a point of reference for them in the future, nobody here knows exactly how many of these were imported to the US by SSR , they have been selling them for about two years now, only one owner showed up in the forum, that I am aware of, and he sold his, so as of now you may be the only member that has one that is currently posting.

Let's hear! Your experiences may help also other people with different bikes as it will provide problems, solutions and sequencing of activities

Quote:

---

Originally Posted by MJH

You should write it all up, who knows if there are any SSR 250 owners that may do the same? Most of these are relatively new, probably too new for most of them to even consider doing what you did, but as time goes on that may change and your thread may become a point of reference for them in the future, nobody here knows exactly how many of these were imported to the US by SSR , they have been selling them for about two years now, only one owner showed up in the forum, that I am aware of, and he sold his, so as of now you may be the only member that has one that is currently posting.

---

Quote:

---

Originally Posted by ShuBen

Let's hear! Your experiences may help also other people with different bikes as it will provide problems, solutions and sequencing of activities

---

+1
:thumbsup:

Added to the great points made by both MJH & ShuBen, it's always possible that anybody interested in doing something similar may stumble across this thread during a Goo.gle or Yahoo search etc. especially Streettechmiata if you added relevant 'tag words' in the field at the bottom of your original post in this thread.

OK so doing this posted 3 major issues to solve. The rest was easy and smooth sailing. The first problem. The oil feed for the tu/xf 250 cylinder head is pumped through an oil passage in the cylinder sleeve through the head gasket up to the head to feed the cam and bearings. This was the biggest issue because the gn250 does not flow oil to the head that way so the hole is not there. To solve this issue, I pulled the passenger side case assembly with the oil filter housing, drilled and tapped a hole in the oil pressure passages that can be very obviously seen with the case off. Unfortunately I didn't think to take a pic before so I only have a finished pic. I used a pipe thread tap set I purchased from harbor freight. And bought a fitting made from brass at home depot that matched the threads with a hose barb on it. When looking at the case you can see a dimple in the top of the case the factory used to drill their hole into the filter housing. I drilled into that area, and installed my fitting with thread sealer. Attachment 17726

Then as I'm sure you could guess. You need to get that oil to the top end. I removed the cam cover assembly and drilled and tapped the upper portion where the cam bearing is. And installed my fitting. I had to grind the fitting down with a cut off wheel as the fitting sat deep enough to hit the camshaft. Then I had to plug off the hole where the oil used to flow into the camshaft so my oil feed I made wouldn't pump oil out. I hoped the head gasket would cover the hole from the bottom so it would seal it. Unfortunately it didn't. Soooo when the cylinder head was off, I found a screw that fit decently snug into the hole from the decked side of the head. Mixed up some jb weld and filled the hole and coated the screw to put inside as well. Seems lame but worked awesome. After it set for a day, ground the screw top flush with the deck of the head. Worked and sealed perfectly. Then to cennect my two fitting I installed I used the hose in the picture. Made for 2 stroke fuel line. Which means its is also OK for oil. Attachment 17727

Nice.

But I wouldn't trust to this silicone hose - IMO, flimsy bastard is simply to close to head and exhaust pipe. I would try to fit something rigid, like copper tube.

Thought - you live (and ride) in Cali, which is for us, who live abroad, hot and dry place. Now that you have external oil line, is oil cooler in you plans?

Yea I do plan on eventually running the oil cooler. And I was going to wrap the exhaust so it wouldn't be so hot near the line. For hose I was planning on getting like a stainless braided atf cooker hose. But for now the other line has been holding up good

You should post this on chinariders.net as well. Many North American based members on there, and I do know of one or two regulars with the XF. In fact, one lives in Sacramento if memory serves me. Thanks for becoming the Guinea pig for this project!

OK on to the next major problem number 2. The cylinder sleeve is physically too large to slide down into the case of the tu/xf 250. Going from 72mm bore to 78mm bore is a pretty big jump. Also with the old cylinder sleeve out it was a little longer by a small amount. Maybe 3mm. But with some measuring and checking that wasn't an issue. I was worried about the sleeve hitting the crankshaft. But it clears fine. So with the sleeve being too large for the whole. From some light research I did that can depend on the year of the tu250 case. But for mine it was too small. Obviously nobody wants to go grinding the case hole bigger and dropping a bunch of metal inside the engine. But at the same time I did not want to pull the bottom end apart. It took some creativeness and carefullness. But I bunched up ALOT of duct tape and stuffed it inside the engine and on everything to catch the alum shavings. That was not re assuring enough for me. I also took a shop vac. Took a pnumatic die grinder with a carbide grinding bit and held them together in my hand at the same time. So as the shavings flew off, the vac sucked them up, the duct tape caught the rest. With the aluminum and the carbide bit the chunks come off big, not like a power so it is very easy to see the large aluminum chunks. I used the gasket as a reference. Don't get me wrong, this was a MAJOR pain in the ass and time consuming. But in the end it worked fine. Before pulling the duct rape out of the engine I used the shop vac to suck up any loose material. The rest stuck to the tape. When pulling the tape. A couple pieces of aluminum did fall in but I could see them and sucked them up as well. Attachment 17729Attachment 17729

And problem number 3. The timing chain tensioner from the tu/xf is not the same diameter or length so it does not fit the gn250 cylinder. Two ways you can solve this problem. If you search eBay for Suzuki chain tensioners there is a fully adjustable chain tensioner you can use. Or you can do what I did. I took a piece of steel plate. Used the gasket and traced out the bolt holes and center area. Cut and drilled the plate. Got a long bolt and matching but. Drilled a hole in the center and welded the nut to the plate. Its a long bolt so it has plenty of adjustment. I ran it down till it contacted the guide then loosend a quarter turn. Attachment 17730

You widen crankcase using only die grinder and steady hand, on a assembled engine!?

Oh man, this is real undertake!

I would not have such courage.

Quote:

---

Originally Posted by Zorge

You widen crankcase using only die grinder and steady hand, on a assembled engine!?

Oh man, this is real undertake!

I would not have such courage.

---

It was a bit of work but didn't take more than a couple hours. Probably took approx 1/8 inch all the way around the bore of the case. Maybe a little less. All in all the whole build took me 2 weeks. Just a couple hours here and there after work. Couple of days ago I swapped the oil and filter after putting 100 miles on the new piston And sleeve. I probably have about 250 miles on it now. And I just purchased a 32mm flat slide carburetor. Which will probably make a nice difference from the 29mm CV carb.

Burt Munro would approve this project.