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Post by Tobyjugs on Jan 18, 2017 0:17:29 GMT 1
Me and a friend have seen an Athena big bore kit for sale at a reasonable price for sale here in Holland. My friend is thinking about buying it but i have told him i don't think it's worth the bother and he should buy some cpi barrels. To be honest i don't know too much about the subject and maybe biased towards the Cheetah's etc because of what i have seen here. To get a fair judgement of the Athena big bore kit i told my friend i would ask the people who know on this most excellent forum  He is thinking about tuning the cylinders and expects about 90hp from them with a standard stroke cylinder. Anyway enough of me babbling on the question is what is good and what is bad about the Athena big bore kit??? and if you don't like it what would you choose as an alternative??? Cheers in advance Tobyjugs  |
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Post by Mr Kipling on Jan 18, 2017 0:46:39 GMT 1
90 Hp from Athena,s yeah he,s looking at popping in a +7 crank an quite a bit of tuning , oh an wiseco pistons too, better off popping in a +4 crank an cpi barrels achieve the same thing / work out better more ( cost effective too )
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Post by Mr Kipling on Jan 18, 2017 0:50:13 GMT 1
Bad points , have to replace everything except the barrels to achieve 90 hp.. Good points cheaper wiser to buy cpi ...
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Post by markhoopy on Jan 18, 2017 0:51:58 GMT 1
+1 the Athena 421 would be 15bhp or so down on a 421 CPI
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Post by LC_BOTT on Jan 18, 2017 11:00:41 GMT 1
Haven't seen mention of a different crank, so I was assuming 385cc? isn't that all you get from a 'big bore' kit? so around 70 Hp was what I was led to believe.
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Post by muttsnuts on Jan 18, 2017 11:37:28 GMT 1
I've just finished doing an Athena kitted YPVS (standard crank) and got that to just under 75bhp, but that had TSA exhausts, ignitech, 28mm PWKs, drilled airbox lid and it took some doing to get it to that
The Athena kit gives better mid range than the cpi cheetah barrels, but after around 7.5k it gets mullered by the cpi barrelled stuff
I have a 421 Athena bike due in for set up etc, once I've done that I'll be able to compare 421 Athena to 421 cpi Cheetah etc
It really depends on what he wants, big horsepower or a really tractable/rideable bike for the road, plus as already mentioned, most people throw the Athena internals away and just use the barrels with Wiseco pistons and the likes, so the cpi route can work out better in the long run
HTH
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Post by Mr Kipling on Jan 18, 2017 12:29:07 GMT 1
Haven't seen mention of a different crank, so I was assuming 385cc? isn't that all you get from a 'big bore' kit? so around 70 Hp was what I was led to believe. Standard Athena bore kit 392cc / but if he wants 90 bhp then no option +7 crank etc.. If he wants to use standard crank still be better off buying 392 ( 400 ) cpi kit.. |
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Post by 4l04ever on Jan 18, 2017 13:45:07 GMT 1
If it is for the road, stick with something with power valves....otherwise you are going backwards in evolutionary terms...
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Post by Norbo on Jan 18, 2017 16:34:55 GMT 1
for usability and all rond best power on the road Athena are the best . you can get more power from bigger and other kits but are not so usable for the road or daily use . a 44mm crank is a nice up gread as well if you need a crank any way why not but even woith out 1 they are still a great top end
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Post by Tobyjugs on Jan 18, 2017 22:49:22 GMT 1
Haven't seen mention of a different crank, so I was assuming 385cc? isn't that all you get from a 'big bore' kit? so around 70 Hp was what I was led to believe. That's right BOTT he wants to use standard crank |
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Post by Tobyjugs on Jan 18, 2017 22:52:53 GMT 1
Thanks for all the answers i will tell him to read this thread.
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Post by JonW on Jan 19, 2017 0:23:24 GMT 1
may be useful: 2smoked.com/Yamaha_RD_%26_RZ_upgrades_-_RZ350_RD350_Big_Bore_Primer.htmlPeople ask me if id build another Athena and when I say 'no' they panic... But thats only cos I have one and I built and wrote about it when few others had done it at all, and no one had written it up. so if i did a big engine again Id use another top end cos its different. The Athena top end is good value for money, even when you sell off the bits you dont want. it works well and revs up really fast which has something to do with the nikaseal bores I think. I found it a cost effective way to get back a nice powerband hit yet still be streetable, as so many of the other cyls are really for racing banshees. There are more cyls hitting the market daily it seems, its hard to keep up but there is lots of good info out there about Athena and you rarely see complaints about them. |
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Post by Mr Kipling on Jan 19, 2017 1:30:15 GMT 1
As a complete bolt on kit , yeah Athena kit good value especially if u shop around , my first post was referring directly at 90hp part from Athena,s.. .. Its a shame Serval CPI barrels etc aint as universally available around the globe at the same price as our American counterparts buy them for .. Best part of all regards to athenas , u don't have to get both barrels re nikasealed at the same time if needen,t be..
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Post by Tobyjugs on Jan 21, 2017 20:01:32 GMT 1
So It's fair to say the Athena kit is a sensible choice for someone who actually uses there bike regularly.
Has any one had any problems or mechanical failures they could share on here or is it all positive?
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Post by wallcraft on Jan 22, 2017 9:51:41 GMT 1
From all the posts and research I've read it all seems good from buying to building, just the usual set up frustrations and how deep your pockets are! Big investment if done completely but seems worth it.
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Post by sarnia1 on Jan 22, 2017 10:02:56 GMT 1
what ever you build after a month or 2 you will want more power
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