Well.... my dad and I are going to take out the engine this Saturday. We'll crack it open and see what the damage is. Hopefully it's nothing too extreme. I like the idea of the 155cc kit. However, I'm curious if the extra 5cc is noticable or not.

This may also be a good time to change out the rollers to 10g, a 1500rpm clutch spring, and then Unifilter and 130 jets

the 155 kit with a cam does add some power. thats what I have in my wifes. when you remove the wrist pin check for marks in the small end of the rod

My buddy had a similar dilemma. He put some magic potion in his while it was running and it started cooking the rings, and started burning oil and at the end was actually not burning all the oil but half cooked oil was dripping out of the exhaust lol. He went with the 155cc kit, because it was cheaper than trying to source a piston/rings, let alone an oversized piston and rings. A genuine honda one may work but I haven't tried it. The 155cc kit I think at the time last year was 150 bucks, came with the gaskets we needed and worked perfectly. I rebuilt it for him (while he was learning), and we put in a better cam too. I think the only way your going to notice the 5cc difference (which is like 1mm oversize) is if you get a bigger carb. jetted perfectly, the bigger cam and some extensive cvt mods. We played around with it for quite a bit, and my stock engine carter talon with cvt mods still kept up with him. For the price, the 155cc kit is the way to go if you're already going to rebuild it anyway.

Thnx for all of the input. I'll know exactly what's going on here in a couple of days.

I'm still a little curious to know if anyone has swapped the engine. I've read a little about the UFB. But I'll have to search a bit more to see who else has done this.

We put a 377cc rotax twin cylinder snowmobile engine/transmission into a twister hammer head buggy. Lots of work but lots of payoff. youtube link: http://www.youtube.com/watch?v=_NjkneckIE8

I put a CN250 in our Baja Dune, now I'm making it irs. http://www.buggynews.com/topic15574-40.html#156885[url][/url]

Greg

**Update**

We opened up the top end and have had a good look at it. The piston shows wear and some grinding. The cylinder wall is scored on opposite sides near the top. The flywheel puller that we have is too big so we couldn't get in to see the crank. I will be definately going with at least a 155cc kit.

Since there isn't much price difference between the 170cc and 180cc big bore kits my father is going to check with a local shop to see what they would charge to do the boring. If it's reasonable then I would be open to going in that direction.

A few questions that I currently have:

1. 180cc kit: are there any known issues with boring out this much? Will I need to add anything beyond a 30mm carb and uni? Are there overheating issues? Will it be a significant increase in torque or top end? Is it safer to go with the 170?

2. Rollers and Sliders: I'm not clear as to what the exact difference between these two are. I've read that the stock Crossfire comes stock with 10g rollers. Is there any performance increase by going with 9g rollers or the 12g Dr Pulley sliders?

3. The Cylinder sleeve: What is the best way to get this out of the cylinder? Does it screw out or do I need to use a block of wood and hammer it out the top?

4. Stroker Crank (which seems to be the most expensive ) and stock cam VS. stock crank and A11 cam?


5. Where's a good place to get a pair of 3 point Y harness for the Crossfire. I don't know how to weld so many of the deals on Ebay are out at this moment.


I'm ordering some parts tonight. The wife and son will be out of town this weekend so I'll get A LOT of time to do some work to both of them.

A big bore kit is going to give you mostly low and mid-range, and you'll get the top end from the UNI and carb. A performance exhaust would definitely contribute as well since you're going to be able to have more combustion going on - you may as well have some place for it all to go!

On important thing when boring out the crankcase (especially if going to the 63mm - 180cc kit), you don't want to hit/puncture the oil channel in the side of the crankcase wall. When boring it out to this size, you come dangerously close and will have a very thin wall there. If it is breached (or nearly) and even if it's repaired, you're going to have a weak spot there that might be trouble in the future. This is the reason that we only carry up to the 62mm kit (175cc).



Best to make sure what weight you have currently, and then decide based on what kind of riding you do the most. Since you're looking at a big bore kit (and maybe an A11 cam), you're going to have plenty of low end. I say go for the 12g sliders if you don't need crazy low end for where you ride.



It should just (more or less) slide right out when you pull it.



I have no opinion or advice on these two.

-Mike

http://www.youtube.com/watch?v=SuXjt9jRz3U&feature=player_embedded

This is a stroked, 180bb, a12cam,large port head racing my hh250. Night and day. I believe I would have to do this to any 150 I might own iff I'm gonna ride it

The stroker is where it's at. Longer stroke means a faster spool. I was climbing hills at half throtle that others were wide open on and some just stuck. In fact I've yet to go over half throtle on a hill unless I want to go faster while I climb. I run 24in tires on a small sproket, with 12g sliders, and a12 cam. I am in no way geared low yet I got so much low end it's crazy. None of the other buggies I've driven have had as much torque.