350X big bore replacement parts

[6speedthumper]

I have a Powroll an 11:1, 5mm big bore kit in my 350X. Bought it back in 2013 and the bike runs great to this day. Lately, I've been considering stockpiling certain parts, and replacement parts for this kit is one of them.

Since they are no more, did anyone buy nos from them? Or have any additional info?

I see Mickey has a 502cc kit, but honestly it's too much for my needs.

[big specht]

You can never have to much power. Just to much throttle ! Lol

[6speedthumper]

So true! Just finished up 4 days of riding at Hatfield. Leaving for home in the morning.

But, what I meant was, that displacement will be handicapped by the cam and porting I currently have. My bike is very efficient as is, and I'd rather stick with the current 395cc, or 1mm overbore. COMETIC has the 86mm base and head gaskets in stock. I also contacted JE pistons they made Powroll's pistons (iirc), and am awaiting a reply.

I did find that LA sleeve has a 425cc sleeve, but is out of stock. I was just hoping someone had a nod Powroll kit that could be purchased.

[big specht]

Lol we might have only seen one other atc on the trails down there. We are always riding atc’s when we go down.

[350for350]

Way to represent, guys. Good job! I like doing the same when I go riding in Colorado.

[6speedthumper]

Represent I did! Got loads of attention this trip. More so then previous excursions. Bike ran like an animal the whole time, too. Probably covered 150+ miles in only 3 days of total riding. My wife did great, as well. The Warrior I put together for her, over a year ago, is finally broken in.

Anyways, back to the topic at hand. I called JE today, and the guy I spoke to wanted specs or order numbers to go by. Didn't sound interested in doing any digging.

I did email Wiseco and asked if they would be able to make a .020" over, 11:1 piston, using the shelf pistons they have as a reference. Said .020" over, big bore piston would be 86.5mm. Maybe I can get further on that front, because I'm not tearing down my perfectly good running X to get a number off that piston. Only photos I have of it are installed and the part number is not on the crown. I vividly remember it coming in a JE box, from Powroll, with the sleeve and gaskets.

[ATC-Eric]

I have 400cc kits I produce. I set it up to be a bolt on kit, so you don't have to mod the cases. Basically the sleeve I use is about as big as you can fit in a stock crankcase.

My kit runs an 86mm piston, putting it at 400cc's.

https://i.imgur.com/8Eui3uY.jpg

We designed and built these kits back around 2009. Had CP laser a head, and design this specifically for our application. Pistons are lightened, and gas ported. All 15 of the kits I sold 10 years ago are still out running around to my knowledge. So there's a good track record to follow on them.

https://i.imgur.com/qeeXRi1.jpg

https://i.imgur.com/1Jc3w5g.jpg

I've got sleeves, pistons, and gaskets on hand. Waiting on more cylinders so I can produce some more right now.

My kit costs $650 shipped in the continental US. Outside the US its $600 plus actual shipping. (plus a cylinder core).

[6speedthumper]

Pm sent to atc-eric.

[Dirtcrasher]

I'd prefer Erics kit over the 502 all day long, no need to bore cases.

I've got a 452cc and had to bore my cases, but I have a mill so it was easy. Once it wears out, that's it, last bore on that sleeve. It wasn't designed very well IMHO....

[6speedthumper]

I'd prefer Erics kit over the 502 all day long, no need to bore cases.

I've got a 452cc and had to bore my cases, but I have a mill so it was easy. Once it wears out, that's it, last bore on that sleeve. It wasn't designed very well IMHO....

Having the Powroll kit, I am in agreement with preferring Eric's kit over the larger big bores. That's a whole lotta piston with not much stroke. I like the stability, and usability, of the 86mm kits.

[_ATC250R]

Eric any idea of the power increase on this kit? And how is the ridability of it verses stock? Does it get hotter than the 350 after a day of riding? Just curious.

[ATC-Eric]

Eric any idea of the power increase on this kit? And how is the ridability of it verses stock? Does it get hotter than the 350 after a day of riding? Just curious.

If one of my kits has been on a dyno, I'm not aware of it. I need to get a few bikes together and find the closest one to me to get some numbers.

The kit is very reliable. I beat on mine for close to 10 years. It still ran great, didn't smoke etc etc when I just tore it down this year. And I should say I tore it down to inspect, and measure out what I needed to, so I could start building them again. The other kits we sold back in 2010 are still running around out there without issue. I never got a phone call for an over size, or to tell me we had a failure.

When we first built these kits, I installed one on my bike without ANY supporting mods just to show how bolt and go it is. Stock carb, air box cover, stock pipe, all of it. It had UNGODLY amounts of torque. BUT it didn't let enough heat out of the engine, and it did get pretty warm on rides. After an aftermarket pipe all was well. These kits have been riden coast to coast without issue.

[leevarnado]

Interested in one of these kits for a 350d,what cam do you recommend for torque .

[ATC-Eric]

I don't have much on cam experience. The kit itself offers a good amount of increased torque as is. If I was going to add a cam for all around riding, I would suggest a mild grind if anything if you're not looking to get too aggressive. I will have a good amount of these kits ready in the next 2 weeks. I've got another batch of pistons on the way, and a ton of cylinders to work with.

On that note, my kits require a core cylinder. Do you have one ready you can ship out?

[6speedthumper]

Cool! I'm still wanting a kit, and have most of the money. But, I'm trying to get together with a guy who has a complete top end from a 350D that he's willing to sell. If I can't get that nailed down, I'll be pulling the trigger on a kit.

[Shawn Powell]

I don't have much on cam experience. The kit itself offers a good amount of increased torque as is. If I was going to add a cam for all around riding, I would suggest a mild grind if anything if you're not looking to get too aggressive. I will have a good amount of these kits ready in the next 2 weeks. I've got another batch of pistons on the way, and a ton of cylinders to work with.

On that note, my kits require a core cylinder. Do you have one ready you can ship out?

Why a core cylinder ? Forgive me for being late to the party, is it just a sleeve or do you bore the pistons? Could I just buy the parts ? I have a local guy who can either press the sleeve or bore it out. Also what’s the compression ratio on these ? Thanks.


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[ATC-Eric]

Why a core cylinder ? Forgive me for being late to the party, is it just a sleeve or do you bore the pistons? Could I just buy the parts ? I have a local guy who can either press the sleeve or bore it out. Also what’s the compression ratio on these ? Thanks.


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Its all good. I install a new custom sleeve into a stock cylinder core. It keeps the overall cost down if I don't have to supply the cylinders. BUT I do offer to sell one of my cores for a charge.

I haven't figured out what I want to do just a parts kit for. It would likely be $550. There's not a LOT of time in sleeving them, the bulk of the cost is in parts. And CP is PROUD of their pistons lol. Like way proud.

Compression ratio is 11.5:1*.

[Shawn Powell]

Its all good. I install a new custom sleeve into a stock cylinder core. It keeps the overall cost down if I don't have to supply the cylinders. BUT I do offer to sell one of my cores for a charge.

I haven't figured out what I want to do just a parts kit for. It would likely be $550. There's not a LOT of time in sleeving them, the bulk of the cost is in parts. And CP is PROUD of their pistons lol. Like way proud.

Compression ratio is 12:1. You get a lot of feedback from people saying 12:1 is to high for pump gas 91-93. It is not. If your machine is properly tuned, it will run good on 93. I ran mine for 10 years on 93 without issues. Hell we used to add premix to our thumpers to bump compression on top of that lmao. (that wasn't the original intention, but that's basically what we were doing)

Yeah sounds good. I’ll send you a pm. I’d do just a parts kit. 12-1 is fine on pump. I have a 1mm over wiseco 12-1 now. I’ve ran it hard on 91 no issues. Ran it hard on 100 also. Felt no difference. Exhaust smells better lol. I’ll be in touch.


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[ATC-Eric]

I have an update. So the 12:1 ratio is what I went off of from memory. When I got the pistons going again through CP I had asked my rep if they were 12:1. He simply told me that looks right. Well after all the debate on compression ratios, I had him dig further back to the original build specs. It is in fact 11.5:1. NOT 12:1. Sorry for any confusion.

[6speedthumper]

Works for me.

[ATC-Eric]

As stated in my other thread, I do have a higher compression option. I've got a different style, thinner head gasket I can offer. It requires race fuel.

[Native302]

ATC-Eric, do you have these kits still available? My 85 350x needs freshening up and this kit looks amazing!