Engine Opinions

Hi Alan,


If we can sort the few bits and dad has his way then the answer is yes.


Eddie

Hopefully get the new fork seals sorted and the front brake sorted this weekend, also going to try and get it registered.



Eddie

Well the fork seals and the brake are now sorted, just need to run it up again and check everything over then take it testing.




Eddie

Alans posted the blank and arrived yesterday morning, thanks Alan will settle up with you when I see you.
out of interest we still having issues with the bank transfer ref ignition - call you later on this.

For - Terry (Dad)
rough turn the od to 70mm roughed.
machine spigot diameter The liner spigot (cylinder head bolting/location diameter should be no biger than 72/73mm diameter, ideally maximum 5mm thick, so when stud holes drilled still leaves complete ring for locatiing the head, ie no reliefs for the cylinder stud holes.

finish bore piston bore to 55.8mm fine finish
fine finish liner diameter to 68.8 69mm maximum. no taper fine finsh is ok will lap/polish with "time saver" any errors.
I need a 6mm carbide end mill for the transfer ports the carbide one I had is broken, but I still have the mandrell for the lathe to do the transfers on we spoke about.

we still have the cast iron laps for bores 55 and 68mm bores on taper mandrels for polishing so no issues on the bores just the o/d
so can you make a lap quickly for the O/D of liner after fine finishing, I feel it will be quicker than asking others or asking a machine shop to do it, while I'm sure they would do it, time is limited, so be quicker to do it ourselves.

The liner interference has been adviced at "size for size" or clearence of 0.0001" to 0.0002" tenths maximum (no interference is adviced), size to 0.001" clearence is ideal.

Do not take anything off the ends (liner length) as its 114mm so correct length, or minimal to clean up of say 0.004" top only.
you suggested one end is turned the other milled, I would suggest the top side is made to the turned end, leave the milled end ass it is.

if you dont understand this call me I, leave message I will return your call. I intend to collect it on my way back, so hope you can have it ready by next friday latest late afternoon.

will discuss rest etc etc later in the week.

regards Derek

Good Morning All,

With regards to a rev range and power band for a 175 is the a starting point to look at or is this all down to state of tune?


Eddie

Ahh the powerband!
If you go for average ish transfers and exhaust timings (for instance 84/85 ATDC exhaust and 64 BBDC transfers) then you should work your exhaust to a usuable powerband of 7,000 to 10,000 rpm as that is what it naturally will want to run in. If you make your exhaust to work at higher revs then you will compromise the general output and will not really have a strong motor. In other words make it all work together.
Hope this helps'
Alan

Hi Alan,

Thanks for that and yeah it does help, just wanted a rough basis to expect to run to for testing this week.


Kind Regards


Eddie

Well we went testing today and dad got about ten laps in but plagued with problems

Well done the Pickerings!!
You have at least got out there for the first shot, and you now know what you need to do to get the beastie sorted!
Good luck with it all and hope to see you at Cadwell for the last meeting.
Alan

Looks very light, lean and mean Ed!

Keep at it....

Hi Alan & John,

Thanks for the comments, well dad enjoyed getting out on a track for the first time and riding the bike for the first time and has got the bug. The bike started up no problem and warmed up okay but when dad got out on track it just would not rev and was spitting alot of fuel out the back of the carb.


Eddie

Hi Edward,
Sounds like Dad was running a very over rich main jet in the carb... Classic symptoms, but very safe on a first run, hope it got better through the day?
You should have said you were at Mallory and I would have fetched down a bag of spanners to help...!!
Alan

Good advice from Alan, Ed -- and tell your Dad to get into the habit
of keeping at least two fingers on the clutch lever when you have it
running clean & sweet because it is when running close to optimum
-weak carb conditionthe two-stroke likes to seize its piston.
A quick squeeze of the clutch lever prevents a lengthy struggle --
with a locked back wheel.

Go for it and Good luck!

Hi John,

Dad has always had the habit of keeping the twins on the clutch lever as he used to do it riding my gsxr on the road, he could always use his right hand as the front brakes were non existent!


Kind Regard



Eddie

Had the crankcases apart and found the missing item, gonna get it back together and then hopefully sort out the piston and barrel again.

Eddie

Hi Ed nice pic's, are you running that cylinder again? Only ask as I had a simular misfortune once
and the cylinder was honed, new piston fitted and even though it did not look pretty it didn't make a
difference to performance. I see you have a 4" crank - it thing it may struggle to pull away. And a
4speed box, chat with derek - I think he knows a way of making a decent?? box by swapping the two
middle gears over or something.... Happy fettling....

Interesting comment there Mike!
Struggle to pull away -- with a 4" crank -- seems there wasn´t so much of a mystery about big
flywheels all along? The Rossi Red Herring trick ey -- to get us yacking?!

The big-heavy ones versus the little-light ones debate was never concluded -- much like you never
showed the other end of the broken Lay-Shaft, did you?

Glad I met up with you at Cadwell -- my Missus reckons you are a nice young man!!

Cheers!

Hi Mike,


Thanks for the comments on the photo's, just trying to keep the chat going on the forum. We may well try the barrel again although it is bored out to as much as it will go. I don't know anything about the crank although dad said it did seem to pull well in first but then we had all the wrong carburation on the test day and dont have anything to compare it too.


Regards


Eddie & Malcolm