nf75 engine has arrived

Got home from work to find the nf75 engine I ordered had arrived, a preliminary look at the top end had determined that it wasn't seized but had been killed by idiocy.

The piston had been run back to front and snagged the top ring, it has plenty of wear and carbon on the piston to suggest it had run for a while like that before the ring gave in.

Unfortunately this has caused some damage not so easily repaired, the major problem comes because the cylinder is alloy with a steel liner and the ring jamming has forced the liner downwards slightly (fraction of a mm) but that was enough to crack one of the stud holes in the lh case and has damaged the top and bottom edge of the exhaust port

The lower edge has a pretty big lip that sticks up past the main port casting so might be able to grind it flush and the upper might not be to high as to stop me from raising the port height, the problem I think though will be in getting the liner pushed back up flush so the head surface is flat again although i could probably get away with skimming the top down and running a head gasket as no gasket was fitted originally by the looks of it.

The piston does have a 12mm wrist pin as apposed to the 10mm on a camino/ hobbit but sitting it side by side with a +1mm pa50 piston they are identical height and the rings grooves line up perfectly, I haven't pulled my calipers out to measure the wrist pin centre line yet but they look like they are the same distance from the crown.

I will have to pull my impact driver out to split the crank and measure that up but I don't think it will be usable tbh the mains are rough and the big end feels notchy.

The stator cover is cast aluminium too so will be nice and strong for a pull start conversion.

TL;DR

engine has arrived not usable as is but will be measuring up when I get the time.

Re: nf75 engine has arrived

just a thought if someone scans a stock base gasket and uploads it as a template I can print it off to see how it lines with the bottom of the nf cylinder and the cases.

My camino is in the back of the workshop at work and I don't fancy stripping it down just yet so if someone can measure the cylinder height and stud spacing etc of a standard cylinder that would help to get a comparison going.

I will take pics of everything once it is all cleaned up and measured as well as the cylinder head volume etc

Re: nf75 engine has arrived

looking at the starter clutch and kickstart I would say that the starter clutch is purely for bump starting the nf as the kickstart gear locks onto a smaller gear behind the clutch its self.

As the kickstart goes down the main cresent gear moves to the left to engage the smaller crank gear, I would say the nf cases would be a great way for people doing dual variated conversion of other bikes to get a solid kickstarter.

the variator end of the crant looks a lot beefier than the pa50 but it seems to share the same bronze bush style big end. The flywheel and points cam look the same on the other end though so chances are the uprated flywheel and cdi stator kits will fit this crank too.

Re: nf75 engine has arrived

Hi mate.

Did you end up doing much measuring? I have a whole nf75 and would love to know what parts are cross compatible with its engine

Re: nf75 engine has arrived

No mate, i never got chance to do much much more a friend of mine begged the camino off me for a project so the nf engine just sat in the shed.

The nf engine got sent for scrap last year along with a couple of avanti (garelli) single speed engines and various moped/motorbike wheels and stuff that had sat round for years, sods law my cousin needed parts off the avanti's for a champ quad bike a few months later.

I did keep the cylinder head and outer variator pulley though as they are pretty much bolt on parts.

If you have both bikes it would be nice to get comparisons of the rear variators as well, the smaller rear wheel may have a higher rear gearbox ratio for a hobbit too.

Re: nf75 engine has arrived

not my picture i found it whilst looking for nf75 info, it shows the variators and the carb to some extent.

the main clutch bell looks a larger diameter to a hobbit/ camino item and possible a larger diameter rear pulley too, it looks to be the older angled ramp type rather than the helix and peg type used on the later hobbits etc.(edited)

22514954543_7674d199e3_o.jpg

Re: nf75 engine has arrived

nf pics found here including a few more carb pics, looks much beefier.

https://oldschool.co.nz/index.php?/topic/50777-flyingbricks-nf75/(edited)

nf75 carb.jpg

Re: nf75 engine has arrived

picked up an nf carb of ebay for £8.99 (full of water, choke flap stuck etc).

The code on this carb is BB 24BSD, I have also found an image online showing metal choke actuator rather than plastic, that carb says BB 24A[A]OA.

choke is cable operated rather than a lever arm on the pa which explains the extra cable slot on the inlet manifold,

the main jet is a bit chewed up looks like maybe an 82?,

throttle butterfly says 125 on it,

float needle is rubber tipped,

Trying to get the choke pivot out so that i can measure the bore.

I regret chucking the nf stuff out I still think it is an untapped source of honda parts rip building a fast hobbit

Re: nf75 engine has arrived

The nf75 is known as the honda pop in nz, honda nf75 in uk, and honda varie in japan.

Seems a much more popular model in japan now that I know what to search for.

the transmission on the 50cc version of the varie seems to resemble the 75cc version

https://page.auctions.yahoo.co.jp/jp/auction/d289328466(edited)

Re: nf75 engine has arrived

pics of nf50 rear pulley system, again it looks a lot like the 75 version.

https://www.ebay.com/itm/NOS-HONDA-NF50-NF50M-SPROCKET-DRIVEN-P-N-23200-155-010-Genuine-Japan/161429648176?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D49894%26meid%3D4de5f5e5fb3c4f98b9f3e97fbd302ad8%26pid%3D100623%26rk%3D4%26rkt%3D4%26sd%3D182657311376&_trksid=p2047675.c100623.m-1

https://page.auctions.yahoo.co.jp/jp/auction/k313166639

the rear pulley cheek seems like it is cast alloy and spaced further from the rear gearbox than a hobbit is.

Perhaps it is spaced out to allow for the kickstart assembly behind he clutch bell?

the nf50 carb is a BB 22B A[A]OJ, the throttle flap is numbered 115(edited)

nf50 carb.jpg

Re: nf75 engine has arrived

Looks like the same stamped steel shit the pa50 has, that one is just clean.

Re: nf75 engine has arrived

The basic design on the rear pulley looks the same but it looks too me to be a bigger diameter with a cast rear half ifr you look on the yahoo link there are pictures from all different angles.

A bigger diameter rear pulley will let you use a malossi gear set and maintain a closer to stock pull off, the bigger front six roller pulley will let you gain higher top speed so best of both with a wider ratio range in between.(edited)

Re: nf75 engine has arrived

took some measurements of the carb

venturi; 14mm

inlet/rear; 30mm id 34mm od

outlet/engine side; 18.5mm id

roughly 42mm centre to centre on the studs

total length is 76mm end to end.

If the 10mm carbs have enough meat to be drilled to 12mm perhaps these can go 15-16mm?

Would cure a lot of clearance issues created when using bigger slide type carbs, you could keep the standard shock on your stealth ripper.(edited)

Re: nf75 engine has arrived

Dylan Wallis /

Hey, do you have the variator from this?

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