Author Topic: What gives?!? (Read 11373 times)

TheHun · « **Reply #50 on:** January 06, 2009, 06:18:17 PM »

Thanks for that heads up on the fuel filter. I will have it ziptied to the frame. I think my dad has tapper feeler gauges. The bike is getting a full tune. Its super nice to have a shop manual dedicated to the 77-78 explaining everything.

cbr-eric · « **Reply #51 on:** January 06, 2009, 06:44:36 PM »

where did you get teh dedicated 77/78 manual?

TheHun · « **Reply #52 on:** January 06, 2009, 07:16:27 PM »

On the net...I can't remember where...it was a huge download...its a honda shop manual. I just googled it and found it on accident..let me see if I can find it again

eldar · « **Reply #53 on:** January 06, 2009, 07:17:21 PM »

We have it on the site. I think it is in the FAQ section.

TheHun · « **Reply #54 on:** January 06, 2009, 07:21:14 PM »

That one is 1969-1976 clymer i believe.

eldar · « **Reply #55 on:** January 06, 2009, 07:56:49 PM »

There should be more than just that. I know it is on here somewhere.

TheHun · « **Reply #56 on:** January 06, 2009, 08:05:33 PM »

Hope it is...it is an awesome manual.

754 · « **Reply #57 on:** January 06, 2009, 09:58:27 PM »

So you mean you went thru all this.. without dropping a carb bowl...

BTW holding your hand over a carb and getting gas on it , does not mean carb is working..

d@mn 77/78 carbs & their screwed down bowls.. another improvement...

TheHun · « **Reply #58 on:** January 07, 2009, 05:35:27 AM »

Not at the beginning of my troubleshoots, didnt know much about carbs. But I got that new shop manual off the net and that explained how to do it and what parts are what for me a lot easier. So now, I got a clean carb..5-6 hours of cleaning on it

754 · « **Reply #59 on:** January 07, 2009, 05:40:45 AM »

You can get the individual feelers at an auto parts store, probably around a buck. I usually kept them in my impact driver box..

If you feeler set has a removable screw you can add them to your set.

Duke McDukiedook · « **Reply #60 on:** January 07, 2009, 11:35:56 AM »

Hey Hun,
I got a good set of feeler (automotive) gauges from sears (they go down to 0.002 I think). Much more sturdier than the crappy motorcycle ones that shops sell (already snapped two or three of those). Yeah, that is one of the many problems that can happen with sitter bikes with low mileage, carbs have old gas and get all gummy and crappy. Sounds like you are on the right track though

TheHun · « **Reply #61 on:** January 07, 2009, 04:35:34 PM »

thanks. im not cutting corners on this tune up

eldar · « **Reply #62 on:** January 07, 2009, 04:38:13 PM »

Yeah I got cheapo metal feelers and bent the ones I needed to make them easier to use. They have not broken and I have had them about 10 years now.

TheHun · « **Reply #63 on:** January 08, 2009, 04:32:34 PM »

I should have a new update on all the tune up stuff on monday or tuesday when I can work on it a little

TheHun · « **Reply #64 on:** January 12, 2009, 10:33:27 AM »

I GOT SPARK ON ALL FOUR CYLINDERS NOW

I ordered Honda CBR Coils from an F3. Got a nice strong blue spark on all cylinders. A lot thicker/blue spark. Much more than my stocker did. Had to rework the wiring a little bit with some new connections but its all well.

Now I just got to put my carbs back on, new points/condensers and timing. I am stoked that the ignition problem is solved.

FYI pretty much all non coil on plug honda dual output coils work with our bikes.

TwoTired · « **Reply #65 on:** January 12, 2009, 11:24:17 AM »

Quote from: TheHun on January 12, 2009, 10:33:27 AM

FYI pretty much all non coil on plug honda dual output coils work with our bikes.

I'm glad you are happy with initial installation. However, the statement made depends on the value of "work". The coil's primary resistance holds the key to long term success. And, it makes a big difference which SOHC4 model is being discussed. The CB750 seems to be the least sensitive to coil power usage, due to it's larger alternator and battery. Other models... not so much.

Will lower ohm coils spark with a strong battery? - yes

Will they cause faster points wear? - yes

Will they delay/diminish the bike's recharge of the battery? - yes (This impacts the outcome of the first question.)

You can use low ohm coils with less impact on other factors if you use in line resistors to more closely match the original 4.5 to 5 ohm coil primary resistance.

Cheers,

TheHun · « **Reply #66 on:** January 12, 2009, 11:59:01 AM »

They are 3.5ohm coils factory. I will be running Dyna ignition in the summer, not too worried about the points. I believe the stock coils on CBR's are in the 12,500-13,000 range.

TwoTired · « **Reply #67 on:** January 12, 2009, 12:53:24 PM »

Stock points draw power through 195 degrees of crank rotation for each coil. This means that coil draws power 54% of the time with points.
A 5 ohm coil @12.8V draws 2.56 Amps, or 32.8 watts. There are two coils, so that's 65.5 watts drawn 54% of the time for an average draw of 35.4 watts.

You selected 3.5 ohm coils and a dyna S, right?
A 3.5 ohm coil @12.8V draws 3.66 Amps, or 46.8 watts. There are two coils, so that's 93.6 watts drawn 87% of the time (see note*) for an average draw of 81.4 watts.

*Note: I used Marks' (Hondaman) analysis as a basis for calculating Dyna -s On time, from his measurement of 27% of the points off time :
http://forums.sohc4.net/index.php?topic=29545.msg304549#msg304549

Points off time = 165 degrees of crank rotation. 27% of 165 is 45.55 degrees crank rotation out of 360, meaning on time is 314.45 degrees of crank rotation. 314.45/360 equals an 87.3% duty cycle on time.

I was under the impression that the CBR coils were 2.5 ohms, not 3.5 ohms (which would make the calculation much worse from a power draw perspective. Have you actually measured your new coil's primary ohms?

I hope you don't spend much time idling or below 2500 RPM while in operation, particularly with your headlight on, as your battery will deplete steadily till it can't spark the plugs anymore.

Cheers,

TheHun · « **Reply #68 on:** January 12, 2009, 02:27:57 PM »

Yes, coil one primary is 3.48 ohms and the second coil primary is 3.26 ohms.

eldar · « **Reply #69 on:** January 12, 2009, 02:51:57 PM »

3 ohm coils have been a common upgrade over the years. If you have a proper functioning system, you should have no troubles.

TheHun · « **Reply #70 on:** January 12, 2009, 03:52:36 PM »

Thanks. I didn't think it was that bad. and like I said i will have new points and condensers and when those go out i will switch to dyna.

TheHun · « **Reply #71 on:** January 21, 2009, 04:08:47 PM »

Update:

She runs on 4 cylinders now. Carbs are cleaned, new air boots/filter. Full tune up with new points and condensers.

Still runs rough. It idles fine, but I get some smoke coming out-its more grey, not blue. It also pops/backfires quite a bit..especially on 2-3.

eldar · « **Reply #72 on:** January 21, 2009, 05:03:41 PM »

Did you pull the idle jets and clean them? How far out are the fuel mix screws? Starting spot is 1.5 turns from lightly seated.

TheHun · « **Reply #73 on:** January 21, 2009, 05:33:45 PM »

Yep pulled them, and they are turned out 1.25 per manual

TheHun · « **Reply #74 on:** January 22, 2009, 05:36:15 AM »

I forgot to mention. It cuts out/ back fires/ pops/rev rough when you add gas, I am going to check the time in the next couple of days and if I get it timed and still does it..I am clueless. BTW it does not eat any oil. It also has a new accel pump

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Author Topic: What gives?!? (Read 11373 times)

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