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Messages - Underdog1
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361
« on: August 07, 2016, 04:00:36 PM »
Not sure, about the same size and weight I think but the advantage is you can lie them on their side so they'll fit under race rep tail fairings, if you want light lithium is the way to go, so light they feel like an empty box.
Cool, after doing some more research I think if I went for a lithium is just be doing it for the sake of it and effectively wasting money so will go for an AGM. In trying to source a 4 into 1 header, MAC performance do some full 4 into 1 exhaust systems but I don't like the silencers. In going to grab a stubby cone engineering reverse cone when I'm out in the states and it seems a waste to buy a full system to not use part of it. Any recommendations on where I can buy just the downpipes?
362
« on: August 06, 2016, 09:41:50 AM »
I use a motorbatt gel, tipped on its side under the tail fairing, sterling service for the last 18 months, can't remember the ID number but if you EBay "CB750 sohc battery" you'll find em, think it was about £50 from a seller called busters , lithium are ok but don't like shorts so don't fit one until your electrics are sorted, about £130.
Found them in eBay, MandP are selling them. Are physically smaller than the original battery or just lighter? Hasn't got any dimensions on there
363
« on: August 05, 2016, 09:55:45 PM »
I need some guidance on batteries, The spare I had knocking around from an old CBR isn't holding a charge so I'll need to get something for this bike, I'm currently trying to quickly spend my wage on bike parts before my other half makes me be sensible. I want something that's smallish and will have the juice for electric starts. I'm not going to run indicators and my headlight and tail light will probably be LED. Not sure whether it's best to go for AGM or Lithium and what amps/hour I'll need. If anyone has any brand recommendations then please fire them over would be good to short list some likely contenders and see which gives the best bang for the buck 
364
« on: August 05, 2016, 06:26:43 PM »
Unfortunately the CB750 engines weighs 93kg otherwise you could have bought a replacement  , lots of cheap spares out there though so make yourself a shopping list.
And not just spares, aftermarket parts are way cheaper too. Got a long list of stuff I'll be picking up from 4into1 as I'll be popping into San Fran for a day or 2. Basically I'm heading all around the south west so Vegas, San Fran, LA, San Diego and wherever else I feel like going to.. I think Carpy is somewhere around those parts but if anyone knows of any other decent supplies let me know and I'll check em out
365
« on: August 05, 2016, 09:23:49 AM »
If you are going to use pods you'll need bigger main jets, I've used 135's in mine with a 4 into 1 exhaust and the mixture was bang on when dynoed, also check out my thread "how to make pod filters work", (no roll eyes on this forum , it's a league of gentlemen!), spindle spinning in neutral is normal, regarding what's typical when stripping the engine?, it's totally down to the engines previous life, have a search around the threads on this forum and you'll get an idea of the problems you might face, but you'll probably enter a world of pain, most do , I've rebuilt various engines over the years but when the time comes to rebuild mine I'm giving it to Trigger and paying for his expertise, the cost will be more than offset by me being able to spend my time out riding my other bikes and knowing the jobs been done perfectly (Trig you can knock a fiver off my bill for that 😄).
Cool I'll check that thread out, I'm also looking at a 4 into 1 so hopefully 135s will be in the right ballpark for me too. Im expecting to have to get my hands dirty with the engine and could easily get someone else on the job for me but as I've never done this before I feel like if I don't do it now I'll never be able to. I'm off to the states for 11 weeks on the 25th with work so will have to put things on hold soon, and in not sure if I want the engine in bits for that long as when I come back ill probably never work out how it goes back together again ahah. On the flip side there's lots of cool bike shops where I'm going and my return luggage allowance is 50kg!
366
« on: August 04, 2016, 09:28:30 PM »
Great news, put the air box on and it will tickover , makes a huge difference with it off, No2 is either not getting a spark or fuel, check the HT cap is firmly screwed to the HT lead first, if that doesn't work, swap the cap with one of the other caps, by actually unscrewing the caps and swapping them over, don't swap the leads,and see if the problem follows the cap, if that doesn't work check the plug is getting wet with fuel if it isn't you might have a blockage in the carb, but before anything else try with the airbox fitted, try holding revs at 5k and see if the pipe gets hot, if it does your primary jet is blocked on that carb, holding higher revs means it's running on the main jet, regarding the hissing god knows, is the breather in the top of the cylinder head clear?, pull the pipe off for now.
PS video link doesn't work, YouTube is more reliable.
Good call on the breather, took a fair amount of compressed air through it until it finally spat a glob of something out. The hissing ceased after this. Couldn't actually get the airbox on! It didn't come fitted to the bike and it's like the plastic boots are too small to fit on the carbs, maybe it's just the ancient plastic. In going to go down the pod route (cue eye rolls) so not too fussed anyway. Checked the HT lead for cyl 2 and got a faint click when I pressed down hard on it and the cyclinder seemed to fire properly after that so I think it's just a dodgy cap. Going to pull the engine out when I get a chance as I'm getting the frame powder coated, even though I'm inexperienced I'm up for opening the lump up and refreshing whatever needs doing to keep the old girl running for another 40 years. What are the typical things that need addressing? Finally I did notice that the final drive spindle for the front sprocket was spinning when revving the bike in neutral - is this just due to there being no sprocket or chain attached or is it some sort of fault? Cheers!
367
« on: August 04, 2016, 06:17:18 PM »
Aha progress! had the carbs off again, blew all the airways with a compressor and plenty of carb cleaner, reassembled and i think i had the float valves in upside down! although i did reassemble how it was when i took it apart. Cheers previous owner. Chucked the carbs back on the bike and used a hairdryer this time to soften up the rubbers which made it 100x easier. Tried to kick her over and didn't get anything, checked the battery and it was like 7v. Got a good battery to jump it off and still couldn't get her going and by this point i imagine i had flooded the plugs so i took the choke off and kicked her with a wide open throttle and she sprang into life!! http://sendvid.com/mw9r6td9 - Vid of her running Now she wouldn't idle but thats probably due to the carbs not being set up correctly and not having an airbox on but she ran as long as i kept her at about 2000rpm. Not all good news as cylinder 2 didn't seem to be firing right as the downpipe was only slightly warm compared to the others being too hot to touch, and after i switched her off i could hear a hissing and drips of oil coming from the left hand engine cover.  What do you think the issue could be? I plan on pulling the engine apart but its good if i can't perhaps pre-empt possibilities by doing some research Overall a definite step in the right direction!
368
« on: August 03, 2016, 09:12:13 PM »
Did the float valves look ok?, did the little spring loaded pins in the float valves spring in and out?, did you check the float heights?, I found a good "how to" online for PD carbs which mine has, try googling for one for your earlier type carbs, next time you replace the carbs heat the rubbers up (carefully) with an electric hot air gun, they harden with age and are a pig to get on if not softened, the trouble is that because you don't know what previous owners have done it's going to be a bit trial and error, it's got to be a float related issue, here's another thought, do your floats float, they could be punctured and filling up with fuel, that stops them floating up as the bowl fills and stops them pressing on float valve via the arm to cut the fuel off.
Yeah that little nipple on the float valves all spring in and out as they should. I'm going to take them off again tomorrow and check what you've mentioned. I had all the floats in a bowl of hot soapy water at one point..and I don't remember them actually floating hah. Any reason why fuel would come out of that hole and not the drainage pipes out of interest?
369
« on: August 03, 2016, 05:54:18 PM »
The first picture is for CB750 K0 to K2, you need the arm in the second picture to fit the later forks
Cheers bro Right so today I've had the carbs off, the carb bowls were full of some horrendous gunk but after a good few hours work I've got them pretty spankers  I took the floats, float valves, main jet and pilot jet out. Soaked everything in carb cleaner and gave it a good old scrub. Cleaned out the main body of the carbs lubed the sliders and reassembled. The carbs were an absolute nightmare to get back on, overtime i got one side on it sort of pivoted and pulled the other side out. Ended up tapping one side on with a rubber mallet, tightening up the clamps then tapping the other side on. Got my remote fuel tank hooked up and as soon as i opened the petcock petrol came pissing out of the same place as previous (i had no airbox on).  Mostly came out of carbs 1 & 2 but was still dribbling out of 3&4. Any ideas?
370
« on: August 02, 2016, 06:57:16 PM »
Personally, the only aftermarket carb kits I will use are from Yamiya or kits like Gerben in Holland sells.. Don't get me wrong there could be nothing wrong with other carb kits but they also sell inlet rubber kits and camchain rubber idlers that I know to be inferior to OEM and causing people on the US site horrendous problems. Gerben has the right idea ..he sells the 'O' ring kits sourced in Viton. He's got a really good reputation for rebuilding carbs. Rubber compounding is a science in itself. I worked for a company for 20 years that were experts in it, so I feel qualified to comment. DS will not tell me who he sources his aftermarket rubber parts from or give tech specs to check for myself, so again I have voted with my feet on that one.
http://www.ebay.co.uk/itm/CB500-CB550-4-Four-Keihin-carb-O-ring-set-VITON-rubber-for-4-carbs-/112047503140?hash=item1a168d3724:m:ms0_u4ZL-QLjaYiVzIQED2w
Dunno if he does kits for 750
(Attachment Link)
Thanks for the link but already ordered the other kit mate. Im still searching for a reasonably priced front caliper + all the mounting gear. Little confused as I've seen different types of mounts listed on the bay for my bike (76), some look like this (and so does the schematic in my haynes manual:  and others look like this:  The mounting point on my forks looks like this:  Which type do I need?
371
« on: August 02, 2016, 10:24:00 AM »
Morning.
I have been hanging round this site a lot of late, and I think that I have learned; if Trigger says buy something you should buy it !!
But I still recommend you watch: hackaweek "73 honda CB750 cafe racer rebuild " on Youtube.
R
Yeah watched the first two episodes and couldn't stand the bloke hah
There are loads of people on here (myself included) who have used the Cruzinimage kits as in Trigger's link and they are fine.
As Rob says, if Trigger recommends something you will be OK!
Cheers boys 
373
« on: August 01, 2016, 10:16:20 PM »
Did you remove a retainer from the wheel itself, or from the separate sprocket carrier. Racking my brain here, and only recall 1 retainer on the wheel itself, plus a second larger one on the sprocket carrier.
Ive removed one from the sprocket carrier (no.3 in the pic) and the one remaining is in the wheel hub (no.4 in the pic). I think i even confused myself on that one haha. For the card rebuild should i be ordering one of these for each carb: https://www.davidsilverspares.co.uk/CB750K6-FOUR-1976/part_105211/or will there only be specific things ill need to replace depending what i find on inspection?
374
« on: August 01, 2016, 07:52:42 PM »
There isn't one on the wheel that side, just a thick oil/grease seal. Try levering it out with a tyre lever or large screwdriver, a little at a time on opposite edges at a time. Try not to gouge the alloy of the hub as you do it. Or you can use the bearing to remove it by knocking it through from the other side.
Are you sure about that? I think its no. 4 on this picture in my haynes manual: 
375
« on: August 01, 2016, 04:47:59 PM »
Oooookay,
So a few bits arrived in the post today, my replacement ignition and remote tank which got me a little excited as finally i can see if this thing starts right?
So first thing i notice is in key position 1 i seem to have power, the neutral light comes on, if i press the horn i get a very weak sounding fart noise,no headlight and unfortunately I've already stripped off the brakes and rear light so can't check those right now. Key position 2 the neutral light goes out and the horn ceases to work so somethings going on there. The connectors that go into the ignition connector block short with each other mega easily but i made sure they weren't touching each other and still no luck. Electric start also didn't do anything.
Anyway i thought its worth trying to kick it anyway to see what happens, plumbed in my remote tank (credit to Jamesh_sussex for the link) and fuel just immediately pissed out of carb 1&2 from the areas circled. Haven't got my haynes manual to hand so apologies for the lack of technical terms (and knowledge hah).
is this likely to be stuck floats? Was hoping i could see if it would run first before rebuilding the carbs but looks like this is going to be my next job. Just want to hear the old gal growl 
Hi,
I'm pretty sure position 2 on the ignition switch is the parking lights ie. the front pilot light and rear tail light only, and nothing else..
if so you should be able to take the key out when its in position 2.
keep at it.
Yeah you're correctomundo, realised shortly after i posted  Any idea how i get the bearing retainer off this side of the wheel hub?  Managed to get the other side off with a home made tool but not sure about this side..
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