Engine Opinions

Morning All,

Opinions please, good or bad. Running to lean/rich, ignition wrong etc




















Eddie

Hi Ed

feel more helpful for people looking in to aloow comments they may need to know more information like

what oil you using
what troque on the head bots
what mixture of oil % in the fuel.
more importantly
1)do you know the type of piston std bant 2/3 rings - or is it of single ring race piston type.
2) what is the base skirt clearence - mic the skirt and bore divide one from other
3) clearance just under the rings same process as above
4) clearance just above rings same process
5) finally the ovality of the poston front to bak to across G-PIN axis

People may be able to make more comments with accuracy then.

The combustion head first appears to have had a ring breakage in past but, looking closer - it may well be splatterings of gasget goo, we have this - we believe putting a a little too much ilomar on the base gasket allows it to crush into the transfer ports, then being washed off while running- ending up on the head where it gets very hot, unless anoyone alse got any other theories on this. be very interested to know.?

kind regards Derek

Hi Derek,

We are using Castrol A747, the head bolt torque i believe was 10ft lbs, the petrol oil mix is 20:1. As for the more important information i will wheel it out the other room and put it on the workbench and take it apart and take photos at the same time, may help with the turning over compression i mentioned also.


Eddie

hi ed why not pop down to my dads house, I believe he's just down the road from you, take your bike with the top end off, he will mic' the psiton skirt under rings and top lan, and measure the bore for you, the important info, you can then post it on here, not sure you can take a photo of what the clearance is "well unless you have a magnifying intoscope with a digital pohotgraic size scale of the lense that is ! LOL -

You can then post it on here for all to see.

regards Derek

Hi Derek,

Yeah your dad lives about 17 miles away from us so not far at all, dad's gonna give him a ring in a bit and see when he is free. Well i can atleast take photos of the pistion and bits to add to the folder collection


Eddie

just noted the other comment, on past hard to turning over issue - good to let all into this little gem - but to me it sounds like the clearance is allowing good sealing, can not say good /bad or to big/ too small, as with clearence are so small minor differences can have big effects here.

The rings are clearly doing their job by the sound of it, I would suggest it needs running in, a plug chop to check the carburation in order, before blasting it in ernest. BUT PLEASE MAKE SURE ITS A SINGLE RING OR MODERN JAP PISTON DO NOT TRY USING AN ORIGINAL BANTAM STD PISTON. THE RINGS ARE CAST IRON AND WILL BREAK AND DISTROY THE PISTON BORE CONROD BIG END "THE WHOLE ENGINE".

What you using pump or avgas, be carful with castrol mixed with any fuel - not as flexible! (not sure this is the correct word) as synthetic oils, that do not take on moisture but castrol does. I am not saying castrol is a bad oil, as we used it for many years - many still do and SWEAR by it. Just be carful with the life cycle- it has a shelf life, (never leave cap off for long especially in humid conditions) there are a lot more on here who know a lot more about this subject than me.

Hopfully one of them may respond to your request for help/information, Alan Brown or Tom Miller were very bussy at mallory, but do try and get to stand and chat about yer bike, with both of them at some point during the next meeting, They are both very helpfull on these type of subjects, and tend to be a little more objective both have a wealth of knowledge both been very helpful to me. - they will be able to give you tips, and bits and peices of information, just go and introduce yourself to them.

Alan posts on here try sending him a PM - but Tom Miller does not "I think hes to old for computers" (past it - sorry Tom LOL)! So he does not post on here. anyway he is always too busy in the shed, he looks after so many of us from time to time.

Hopefully some one will respond that can add a little more to this than my limited knowledge in this area. - Anyone !!

kind regards Derek

Hi Derek,

Yes the piston is a jap one with two rings, we are using shell optimax or v power, whichever is the new one. The oil never has its top left off and is kept stored.

Yes i did see that Alan and Tom were both very busy so just stayed out of the way, my dad has spoken to alan before. Havent managed to speak to your dad yet but we currently have the head and barrel off.



Eddie

Hi eddie
Was the engine run for any lenght of time under load or just a couple of minutes in the drive/garden etc?

There not anything to go on really... piston looks like its been cleaned but still has black deposits in the surface
dips. What piston is it? Think pin holes in head are just the casting flaws?

I use Castrol Power1 TTS Its fully synthetic cheaper than A747 semi synthetic too..

More info needed

Hi mike,

The engine has only run for about ten mins on the drive, the piston is a suzuk ts185 piston and i havent cleaned the surface and im unsure on the head flaws. Bought the A747 as i thought it was the right thing to buy and got a deal on it, can always buy other oil if thats better.

Gonna try and get the info advised by derek and not sure what else is needed.


Eddie

mjpowell wrote:

Hi eddie
Was the engine run for any lenght of time under load or just a couple of minutes in the drive/garden etc?

There not anything to go on really... piston looks like its been cleaned but still has black deposits in the surface
dips. What piston is it? Think pin holes in head are just the casting flaws?

I use Castrol Power1 TTS Its fully synthetic cheaper than A747 semi synthetic too..

More info needed

beat me to it Mike, need to run a few laps(or long straights) fully warmed up, then cut the engine via pulling clutch lever in coast to a stop then read plug/head

easy sprinting flat out from the line blast it back and coast to the van

Hi Tony,

Well that was our intention when we took it to wroughton last year but we had starting problems then gearbox problems and by the time we got to go to the line we had carb problems so we didnt to get to give it a blast and try that.


Eddie

good to see you are getting lots of help on this ED - tell my dad he needs to bring with him a telescopic mic for a 2- 3 ich bore size and a 2 to 3 inch Micrometer, he has them and will know what to do. Friday sounds good, I can not make it, but dont forget to remind him about these items, he will forget, as he's getting on now, and lived in B,ham for far too long, I think its to do with all the BS up here. !

Now - piston that is good TS 185 - I have used them, and others use them to.

I did not know it was a 175 - piston tells us this, does it have big/short flywheels on the crank, ? what is the rod ? do you know, is it a puka past racer, certainly looks like it is, or is it road based cafe racer.

Here's an offer, do you have leathers helmet and gear, and have you joined the ACU, I intend to do some testing privatly later in the year, june, if you get a licenece and have the gear, I will invite you along, could be your prelude to your first meeting,
"if you wish"!.

Also tell dad to take with him a timing disc, for the ports we need to check what these are, if you hav'nt got one you need one - so all can advise of the state of tune, and what you need to achive as a starting point, Dad has an original blue print, done by both Herman Mier and George Todd on both 125cc and 175cc bantams, back in the day. 1963/66 ish Herman Miers 175 bantam was reputedly timed at just over 117.0 mph through the speed traps, so I'm told.

Sounds like the others have covered some of the important bits for now - they just need a bit more info to help further.

regards Derek

Hi Derek,

When dad rings him in the week i will get him to mention those bits.

Yes this one is a 175 engine, i dont know about the flywheels but i know from looking at notes it is a yamaha rod. It is a racer not a road bike and has a motoplat ignition and dunlop kr's. Before we got it the engine had been sent away for a complete rebuild and new parts.

All i have done is replace fork seals and try and set the front brake up properly and sort exhaust gaskets and do general loctiting and lockwiring.

A certain pickering senior has got a acu licence and orange bib and all the gear................



Eddie

Hi Derek,

First off thanks for the help and info and your dad for coming round and doing alot of checking and measuring. Have got measurements and gonna put it back together and then your dad has offered to come back and check a starting point we have discussed.



Eddie

good to hear you made some progress - My advice is do not run it again intill we do as discussed with your dad, sounds like a few issues on build, I DO NOT KNOW Andy Tidball, only he had a 200 Bantam that eat gearboxes and produced loads of horses !!, But I never met or heared of him actually racing, only sprinting.

can you let me know where to send the invoices for dads time - I presume it',s 30 days ?
just joking sorry I could not resist it I will be there next time.

Hi Derek,

Yeah it was a good day from the sounds of things and i was lucky to get back from work when your dad was hear so was good to find bits out and discuss things.


Cant believe for one second you are a wind up merchant but you are only allowed in if you are good with drinking ale and teeth drying!


Eddie

In the long-distant past I´d spend a day at Brands running-in two pistons. Several laps at half-to-3/4 of full-power running. Into the pits, off with the head and barrel, with a fine riffling file take off the high spots then go out and blast it for several more laps -- followed by a repeat of leisurely lapping and more high-spots removal and finally belting it really hard for up to half an hour. Very fine file to take off the high spots -- rather than using an emery stone because the latter can leave enough grit in the piston surface to unnecessarilly wear the cylinder.
Why two pistons in one day?
If I didn´t have a spare piston, at a race meeting with me, for sure Icarus-1`s motor would nip-up...
But by this method I never had a full seizure with Icarus-1 -- it would nip-up, I´d catch it in time and with a quick clean up it could be raced again.

Unlike Andy Boyle´s 250 ABS -- when that seized the result was destruction before the clutch could be disengaged.

The Bantam nip-up was something I got really familair with. The engine revs would just suggest a drop... and my fingers would react like an automaton had taken charge and the clutch-lever would be at the clip-on-bar -- zap! Three fingers always on the lever...

Hi Derek,

So what is your opinion from what info you were given in regard to the engine, is it worth me putting the pictures up of findings so far?



Eddie

yes yes please do we all want to see

derek

[quote="Edward Pickering"]

see the mark on the rear of the cylinder wall, is that were the ring is dropping into the inlet/transfer port? I would use the other barrel, these ports are for a reed motor, and a ring pegged on the c/line, I would advise, you need to consider seriously this point, although I have my rings uncovered in the rear inlet/treansfer port to, they are on the c/line of my barrel directly opposite the exhst port.

so are less affected by the movment with it being offset, your may tend to hammer the ring ends and peg and could break the ends to stay out in the port.

it will be interesting to see how the otheres who are more knowledgable than me, to help by commenting on this aspect.

regds Derek

hi eddie ,can you tell me what con rod and small end you have there please ? best regards adam.

Hi Derek,


Have just got in from work and spoken to dad and no the rings dont drop into the port as dad has checked them already on saturday as per the discussion he had with you on saturday.

We have the spare barrel and dad is gonna have a go at finishing it off as a back up as per discussions with your dad.


Hi Adam,

I am still in the process of finding those bits out exactly but in dads project it is a maico 250, wiseco piston and he is gonna check what the small end is.


Eddie

Not seen that cross hatching for quite a long time, I watched George Todd do the same type of crossing on a piston from a stripped egine in the paddock, it had seized, I was quite young and nosy at the time, so followd him to see what he was going to do with it, he washed it after stoning in soapy water he used wire wool then a brillo pad ?
I was a very inqusitive 10- year old.

dad does this but with dimples not lines, in order to promote beter lubrication, I think the way its done on your piston will creates stress points that could lead to cracking into the skirt.

Derek

Hi Derek,



I have never denied it and hold my hands up that i am green on all of these subjects hence the pictures. Yes your dad did mention doing dimples on the piston so will try that on a spare piston.


Eddie