CB550 Project Scruffy Racer

You want lower resistance coils on an electronic ignition like the Dyna. You'll get better spark, better performance and better fuel efficiency. The resistance in the primary windings effects voltage, so you will get more voltage and better spark with the lower resistance coils. That's why most electronic ignitions are lower resistance (1.5 - 3.0 ohms). Points use higher resistance coils (5 ohms) so they last longer, since higher voltage will cause them to burn out quicker.
 
Thanks Irk

thiught i would err in the side of safety with the 5ohm, 4into1 sell those with the dyna as a kit so hopefully they’ll work ok

snow set to return here over the weekend so testing will be limited to static running once i’ve checked the carbs,
think i’ll also torque down the head and check cam timing whilst im at it

wonder if 4into1 can repeat their superfast delivery time with the coils?!
 
Just spent an hour reading to catch up....great approach and work rate has turned out a rather nice bike old chap, rather nice indeed.
 
Scruffy update

disappointed that cleaning the carbs made no difference i though i should test again for vacuum leaks.

tried with wd40 and carb cleaner and couldn‘t detect any leaks.

so by way of a control experiment i put back in the spark plugs that came with the bike, and it runs great again.

so it seems that my ‘genuine’ new ngk plugs are crap, or the bike doesnt like them!
the only other potential cause is an intermittent ht lead/cap/coil, but scruffy starts on the button every time now just as it did before.

new coils,caps and leads are due in this week so i’m hopeful they’ll give me a reliable and smooth running bike again.

i bought the plugs from a reputable supplier, they have all the right markings on them too, a mystery!

what plugs do you recommend for a cb550?, other than ngk!
 
Where did you buy the ngk? There are a ton of counterfits out there. You need to get them at a realiable seller. Ebay and amazon is a no no. If they are a low price 99% they are fakes. I foundnout the hard way and had 2 completely fail in my CRV.
 
I did buy them on ebay but from a uk seller with nnn,nnn positive feedback.

lesson learned!

i’m going to dissect the ht leads once the new ones arrive, see if they are the cause and i’m falsely accusing the plugs!

we have a cold snap here in the uk so probably won’t get scruffy out for a week, by then the ignition system should be all new
 
Even good sellers can pass on fakes. Its really bad. They are everywhere and I will only buy from a retailer with direct shipping from NGK.
 
Its cold here today so perfect opportunity to see if Scruffy wants to run on those old plugs

yep, fired right up and with a little throttle ran nice, after a minute or two would idle at 1100 revs

new coils arrived from 4into1 so test fitted those but am awaiting new ht wire and plug caps

oh the irony of parts arriving from across the Atlantic in 1 working day but local parts taking weeks!

2CB0A4BE-A0D3-4396-B60D-3027433F7110.jpeg
 
Ha, sucks eh? If you go to NGK's site you can read how to identify if your newer plugs are fakes or not as well. Might shine some light on the issues.
 
New NGK plug caps and copper ht lead arrived in the post today, so made up the 4 plug leads.

Scruffy fired up immediately and ran well

tomorrow i might swap in the ‘dodgy’ spark plugs to check if they really are crap or if the problem was the old leads ......

still below 0C here so no test ride today but next week looks more promising :)

BD2248A7-65AC-43C4-AE00-5425D8F50594.jpeg
 
Weather is warming up here so am hoping for a test run this week !

over the weekend i investigated the repeating overflow from carb 3

the float valve seemed a little tight in the brass socket, it’s an aftermarket carb repair kit item.....

so i searched theough my original equipment spares and installed the cleanest seat and springiest valve, with a new o-ring

no more leak so far

i also felt the carb return spring strength was only adequate, noticed that my spare original spring had shorter legs, so swapped this in and the return strength is now much better

i know it’s been written before but the quality of modern replacement parts does seem to be lacking !
 
Sderbyshire said:
i know it’s been written before but the quality of modern replacement parts does seem to be lacking !
Click to expand...
Amen to that. For as long as I can afford OEM when it comes to gaskets, o-rings, jets and the like I'll spring for them. Had a nightmare with an aftermarket base gasket and cylinder stud o-rings which ended up causing an oil leak due to poor fitment (cue subsequent engine re-tear-down) - never again. I give the float needle seats a polish with Brasso, really cleans up any crap the carb cleaner might miss.
 
Short test ride and Scruffy is a blast !

significantly more torque than previously, no doubt due to bigger capacity and fresh build.

interestingly i did a compression test at the weekend when the carbs were off

150 -135-135-150

which i thought was a little strange, why would 2 and 3 be a little lower than 1 1nd 4 ?

steve
 
Are your valves set right? may have slightly tight valves on 2 and 3? 15 PSI is at the outer edge of acceptable. Also maybe the slides are not going all the way up on 2-3? so WOT is 3/4 Throttle? IDK but something is off a bit.
 
Carbs were off for the test so not that affecting the compression
i’ll recheck the valves !
 
Scruffy is running well !

i had a test ride today after vacuum syncing the carbs, not perfect but pretty good.

starts instantly and idles well now.

i’ll still recheck valve clearances again, but i did check already so expect them to be correct.

next i’m planning to drill the brake disks , i like the look of them drilled, and rebalance the front wheel as theres a bouncing/vibration at 40mph

project phase is drawing to a close, riding the wheels off phase approaching
 
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