Honda-SOHC
SOHC.co.uk Forums => Project Board => Topic started by: MarkCR750 on May 15, 2016, 01:08:19 PM
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I read that the reason pod filters give issues is that the don't smooth the air before it enters the carb so decided to fit velocity stacks inside mine, then I realised I already had a set in the stock airbox, so ref photos below I pulled some chinese pods apart, enlarged the hole in the plate to accept the rubber velocity stack from the stock airbox, glued the stacks into the plates using "sikaflex" the best adhesive know to man, strong as hell and remains flexible when cured, glued the filter back on to the plate then just clamped the whole assembly onto the bike as you would with the original airbox, the difference is marked, I thought it was running well before but now it's much smoother , has more power, picks up even better and has a dead smooth tickover , best couple of hours I've spent so far regarding modding the bike, the filters were about £20 for the set of 4, the velocity stacks came with the donor bike, so if you've got pod issues do as below, cheers Mark
(http://i1269.photobucket.com/albums/jj582/POR1983/Mobile%20Uploads/image_4.png) (http://s1269.photobucket.com/user/POR1983/media/Mobile%20Uploads/image_4.png.html)
(http://i1269.photobucket.com/albums/jj582/POR1983/Mobile%20Uploads/image_19.jpeg) (http://s1269.photobucket.com/user/POR1983/media/Mobile%20Uploads/image_19.jpeg.html)
(http://i1269.photobucket.com/albums/jj582/POR1983/Mobile%20Uploads/image_5.png) (http://s1269.photobucket.com/user/POR1983/media/Mobile%20Uploads/image_5.png.html)
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very nice
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Good work there Mark. Simple fix and great idea..
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Cheers James, yes it's sometimes the simplest or most obvious things that work best, I'm going to get it on the dyno soon to check the fuelling, not really bothered what power it's making, it's more than fast enough but I don't want it to be running lean, the plug colours look ok but the piston crowns look a bit odd, mainly dark but with small patches of light tan so I'll be happier once it's checked out properly.
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[attachimg=2][attachimg=1]
These are K&N pods on mine which are slightly larger
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I would think you would benefit from a similar set up to the one I have now Greebo, looking at the photos of your filters there is an abrupt step from the filter to the carb, and also no distance between the two for the air to "straighten out", I am in Derby so if you want to take a ride over we could fit my filters to your bike and see what happens, I'm on the dyno Saturday but we can arrange it after that if you want to, cheers Mark.
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Thans for that tip, might help resolve some of my bmw r90/6 issues when I get onto that later in the summer, I just need to get some velocity stacks to mach the massive carbs.... may also get applied to a cb550 special or custom in the future. Have you checked the silkaflex is ok around fuel?
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I would think you would benefit from a similar set up to the one I have now Greebo, looking at the photos of your filters there is an abrupt step from the filter to the carb, and also no distance between the two for the air to "straighten out", I am in Derby so if you want to take a ride over we could fit my filters to your bike and see what happens, I'm on the dyno Saturday but we can arrange it after that if you want to, cheers Mark.
Hi Mark
I see what you mean, I thought it maybe possible to Dremal that step off ? if you look at my set up there is not enough room on my bike to have extended VS.
Thanks for the offer, but at the moment I am laid up & bandaged up, just had carpel tunnel surgery on my right hand, so wont be riding for a few weeks.
What about a meet sometime at CMC clay cross.
Theres the "custom & modified" Sunday on the 24th July, & then on the 7th August there is the "Classic Japanese Sunday"..i will be entering my bike in that show...weather permitting of course.
I hope all goes well with the dyno..
Thanks again
Cheers
Greebo
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Yes I don't think they'd fit, I'm pretty sure mine come half way across the upright frame tube so the panel on yours would be in the way, I've got them off at the moment and the carbs just checking that the intake boots are sealing correctly prior to the dyno, need some new ones really the rubber is hard and I have to heat them to get any give, yes I'm going to both of those shows and the 2 stroke day on the hustler so we'll meet up, might be worth taking the corner off you rubbers provided it doesn't weaken them , should be OK.
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Thans for that tip, might help resolve some of my bmw r90/6 issues when I get onto that later in the summer, I just need to get some velocity stacks to mach the massive carbs.... may also get applied to a cb550 special or custom in the future. Have you checked the silkaflex is ok around fuel?
Sikaflex isn't designed to be totally fuel resistant but there shouldn't be much fuel getting back there, maybe a bit of blowback but I doubt it will affect it, if it causes a problem I'll go over it with some fuel resistant sealant.
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Did I read that right in one of your posts, you've got a good tickover with PD carb's. You must share your secret, is it prayer, alchemy, exorcism? These things were difficult when they were new. Respect indeed.
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Ha, sounds as though I've achieved a miracle then Roy!, yes it ticks over well although perhaps I've got it set a little high at around 1300 revs, I don't know what they should tickover at as standard?
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Great tip Mark - thats the beauty of sharing tips on the forum - without the medium of the forum, everybody would be getting frustrated all trying to achieve the same result! Some way off that with CR but will be using your tip
Phil
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Yes I've picked up loads of good info over the last couple of years on this forum, right , carb balancing time, now which carb is it we use as the master?? 😀
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With PD's that would be No.2 (the only one without any adjustment mechanism). ;) ;D
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Thanks Roy, I remembered as I got the bike out of the garage, they were very close to being in balance, adjusted No4 just a tad, would have gone for a ride but the skies gone very dark here in Derby!
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Greebo, I think the filters will fit your bike after all so if you don't have any luck with the various adjustments you are making it could be worth a try, I put them back on earlier and there is clearance to the frame tube, see photo
(http://i1269.photobucket.com/albums/jj582/POR1983/Mobile%20Uploads/image_20.jpeg) (http://s1269.photobucket.com/user/POR1983/media/Mobile%20Uploads/image_20.jpeg.html)
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Ha, sounds as though I've achieved a miracle then Roy!, yes it ticks over well although perhaps I've got it set a little high at around 1300 revs, I don't know what they should tickover at as standard?
Mark, I am just waiting for a air/fuel mixture screw for carb/cylinder4 which we spoke about, I found that the rich running on that cylinder was due to the air screw not have the o ring in situ, & the spring was stuck but i got it out, that's why it would not adjust as it should, so when I had removed the air mixture screw I also took the pod filter off & I gave the carb a good squirt of carb cleaner via the air intake & where the air screw hole is [screw removed], the carb cleaner came running out & brought out the 0 ring which was broken & had obviously been stuck as the was the spring, so that were the running rich problem on cylinder 4 must have been.
1300rpm idle, That's about right Mark [so I have been told by the guy who re-builds these bikes]
Mine also has a very steady idle, starts usually on the first pull , & when warm it sits at the same steady 1300rpm.
# hopefully I will be at "two stoke Sunday" on the 26th June, depends on how my right hand is, but should be OK by then, if not definitely the "Custom & Modified Sunday"
keep us all posted on the Dyno results.. don't forget the ear plugs.. ;D
Cheers
Greebo
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Hopefully it's just the screw, easy fix, dyno tomorrow, trouble is its gonna rain so I'm having to lash up some improvised mudguards tonight as my electrics are all very exposed, it's not designed to run in the rain!, looking fwd to finding out how much power it's making, I'm sending my modification information form back to the insurance company tomorrow and one of the questions is "what was the bhp when new, what is the current bhp, my guess at the moment is 67 new, 57 now, but who knows I might get a nice surprise 😀
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Been on the Dyno, good news the fuelling is bang on, bad news it's only making 53bhp, he said it's the exhaust that's too restrictive , I'd have to go louder which I don't want to do, it's plenty quick enough as it is, he said I was the first person he'd seen that was pleased with a bike that's making less power than standard!, main thing for me was its not lean, now to get that stupid mudguard off!.
Have a listen on the link below.
https://youtu.be/dzyp3A1TQBY
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says video has been renamed,or deleted by owner,
but glad the bikes running ok
and it looks good
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I've changed it to a YouTube link , remember to put your headphones on and set the volume to 11 😀
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Sounds great makes me want to get out on my bike
Mick
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Only your parents have the authority to stop you Mick, get out there 😀 , the volume doesn't come across due to the iPhone's tiny microphone but even with ear defenders on it was loud, up to 5k it not too uncivilised though which is good news for my neighbor 😀