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rkjjeep
  • Rank:XL Board Member
  • Posts:9
  • From:USA

Date Posted:09/30/2017 10:57 AMCopy HTML

Does anyone know what compression results from the powroll 298 kit?  I think that i what I have n the 250
tuscarawas #1
  • Rank:Diamond Member
  • Posts:553
  • From:USA

Re:298 kit compression

Date Posted:10/01/2017 1:21 AMCopy HTML

Hi there. I have an original powroll catalog and it says the 298 cc kit has 9.5 : 1


JKCanuck #2
  • Rank:Bronze Member
  • Posts:27
  • From:Canada

Re:298 kit compression

Date Posted:10/09/2017 6:25 PMCopy HTML

 rkj,

 I have been trying to figure out what the compression ratio on my as-yet-unringed 80.7ish Powroll piston would be with the stock XL or TL head that I would apply it to.  Simplifying the formula, cylinder volume + combustion chamber volume divided by comb. ch. volume gives compression ratio. Combustion chamber volume includes gasket thickness. (The minor piston dome volume on my piston is roughly compensated for by valve cutouts). Assuming unaltered combustion chamber, the math is:   stock 250  (248 + x = 9.1x)  x  is CCVol.  So, 8.1x = 248   x = 30.6 cc.  For the big bore 298,  (298  +  30.6 = 30.6 times r), where r is compression ratio. So, 328.6 divided by 30.6 =  10.6 , roughly. Just a little algebra, folks.  Some Powroll pistons, at least as shown in old photos, may have had higher domes and, therefore, higher ratios.

  I'm not exactly looking forward to kicking over my Powroll cylinder when that day comes, owing to my 75 year old legs, but we all develop a methodical drill to start big singles, minus the compression release Honda devilishly omitted. I, personally, would love to lay my hands on one of those rare tappet cover CRs that are described on the XL page.   Your competent machinist could probably make a similar one in a couple of hours. Until I find a set of rings for my piston, it will remain only mental exercise.  

                                     

dirty_rotax #3
  • Rank:Silver Member
  • Posts:63
  • From:United Kingdom

Re:298 kit compression

Date Posted:10/10/2017 6:11 PMCopy HTML

 After a lot of searching for the web site I used to buy my new powroll 298cc piston rings, I found the paypal receipt which includes the chaps email.

His email is   T.raymiller@yahoo.com

I paid $60 including post but the rate was 1.39 back then. I have formated my pc since buying them so dont have all the emails, But I'm sure back then he had 2 sets of original rings for the powroll 298 piston

found his web page  http://millervintagecycle.com/

worth sending him a email, I found him very helpfull.   hope this helps your search
dirty_rotax #4
  • Rank:Silver Member
  • Posts:63
  • From:United Kingdom

Re:298 kit compression

Date Posted:10/16/2017 6:30 PMCopy HTML

 I found the original rings for the powrol 298 piston, obviously used but your welcome to them if any use
JKCanuck #5
  • Rank:Bronze Member
  • Posts:27
  • From:Canada

Re:298 kit compression

Date Posted:10/17/2017 11:43 PMCopy HTML

Dirty, thanks for the contact for Terry Miller.  He's fully operational as the operator of the Powroll business.  He has the stroker kits, big bore kits, etc. and was able to find in his parts supply the very last set of 80.75 rings in existence for my big bore TL250 .  Very nice guy, very helpful and talkative. 

His business address is:

T Ray Miller, Miller Vintage Cycle (Powroll Products), 13840 SW Commercial Loop, Crooked River Ranch, Oregon (OR), 97760.   tel 1-541-923-1290

That's about 20 miles south of Madras,OR, on the eastside of the Cascades about 130 miles SE of Portland, a gorgeous morning's ride, a climb up the foothills, past Mt. Hood, the dormant volcano, down the eastside past Warm Springs and Madras. The Crooked River is one of the best tail water fly fisheries in the West. JK

 


dirty_rotax #6
  • Rank:Silver Member
  • Posts:63
  • From:United Kingdom

Re:298 kit compression

Date Posted:10/18/2017 6:40 PMCopy HTML

 Glad to be of help Mate, I wsa sure he had said he had 2 sets, mine and your now,

I still have my original rings which are fine, if anyone is stuck for some


Go soothingly on the grease mud ... as there lies the skid demon! ...





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