Honda NV400

[permy]

Recent purchase of a 1986 honda NV400. Bought cheap to get through my learners period and do things legit. Seller advised of oil leak, bugger all compared to my 30 year old diesel 4x4 so I wasn't phased. Just kept it topped up (100-200 ml per fortnight).

Then out on a ride lost power considerably heading uphill. Bike was hot, let it cool and checked oil and water both good. Rode home, fine once cool.

Next day same thing, same response but was further from home and figured I'd soldier thinking I was through the worst of the hills. Bout 10km later same issue but worse, fair bit of smoke according to mate following.

NOW will start but not idle without throttle. Rear cylinder has very low compression (according to my thumb) and front is good.

I'm thinking rings or valves, there is no obvious gasket leak and no symptoms of water in the oil.

Is there a way to tell without pulling the head off it? How about getting new valves/guides or rings for this thing? From what I can find there are a lot of similarities between nv400 engine and the vt500. will these parts be interchangeable?

Is there another more common engine I could replace this with if parts are going to be a prick to find?

[AllanB]

Rear cylinder has very low compression (according to my thumb) and front is good.


I'm just grateful you didn't stick your dick in the plug holes - to be fair a penis is more sensitive than a thumb so it may be a more accurate way of checking compression.

[Grumph]

Check the valve clearances - from memory those things have screw and locknut adjusters so aside from the lack of access it's fairly easy.
Did the coolant temperature get up ? That one is water cooled ?

[F5 Dave]

You might find another NV engine but you'll be lucky. That's all that's likely to fit, Honda being Honda.

Had the loan of one for couple of months. Actually enjoyed it. But don't tell anyone.

[husaberg]

As far as i am aware the NV400 is esentually a destroked Vt500
Being honda there might also be detail differences in the stators and wiring.

[F5 Dave]

And probably the engine mounts just to be kunty. They are like That.

[husaberg]

And probably the engine mounts just to be kunty. They are like That.

Unlikely as they are in the same family of Engine codes. but nothing is imposible if honda figured it would save them some money.
From what i understand the bros and the NVT650 revere share the same mounts only the engine direction is reversed because of the shaft drive.
On those engines the shaft can be converted to chain drive with Bros/Hawk parts output shaft etc. but it will still run in the wrong direction.

[Old p]

im nw and need yo post on forum but HOW ? thanks

[HenryDorsetCase]

Recent purchase of a 1986 honda NV400. Bought cheap to get through my learners period and do things legit. Seller advised of oil leak, bugger all compared to my 30 year old diesel 4x4 so I wasn't phased. Just kept it topped up (100-200 ml per fortnight).

Then out on a ride lost power considerably heading uphill. Bike was hot, let it cool and checked oil and water both good. Rode home, fine once cool.

Next day same thing, same response but was further from home and figured I'd soldier thinking I was through the worst of the hills. Bout 10km later same issue but worse, fair bit of smoke according to mate following.

NOW will start but not idle without throttle. Rear cylinder has very low compression (according to my thumb) and front is good.

I'm thinking rings or valves, there is no obvious gasket leak and no symptoms of water in the oil.

Is there a way to tell without pulling the head off it? How about getting new valves/guides or rings for this thing? From what I can find there are a lot of similarities between nv400 engine and the vt500. will these parts be interchangeable?

Is there another more common engine I could replace this with if parts are going to be a prick to find?

David Silver Spares www.davidsilverspares.co.uk

www.cmsnl.com

www.econohonda.co.nz


are my three go-to sites for old Honda parts. Try local first obviously - they have a very good range of stuff.

good luck with it.

[F5 Dave]

im nw and need yo post on forum but HOW ? thanks
Hey welcome to the club.

However trikes aren't real motorcycles and are. (Edit, sober now).....

No disrespect.

I'm just saying,

[actungbaby]

\
Recent purchase of a 1986 honda NV400. Bought cheap to get through my learners period and do things legit. Seller advised of oil leak, bugger all compared to my 30 year old diesel 4x4 so I wasn't phased. Just kept it topped up (100-200 ml per fortnight).

Then out on a ride lost power considerably heading uphill. Bike was hot, let it cool and checked oil and water both good. Rode home, fine once cool.

Next day same thing, same response but was further from home and figured I'd soldier thinking I was through the worst of the hills. Bout 10km later same issue but worse, fair bit of smoke according to mate following.

NOW will start but not idle without throttle. Rear cylinder has very low compression (according to my thumb) and front is good.

I'm thinking rings or valves, there is no obvious gasket leak and no symptoms of water in the oil.

Is there a way to tell without pulling the head off it? How about getting new valves/guides or rings for this thing? From what I can find there are a lot of similarities between nv400 engine and the vt500. will these parts be interchangeable?

Is there another more common engine I could replace this with if parts are going to be a prick to find?

there surpossed to be very realible i brought a vt 500 still havent got it going i did the head gaskets .
was a very rough beach bike by looks of it. guy i brought it of is a snap on tools guy in wellington great bloke

he brought as a project so it already been screwed with i think from memory said it ran okay on the mid range up.

i think my coils well they where working but not on all spark plugs two each cylinder . i did a crude take out the spark plugs

and hold to earth to the metal cyclinder fins. and wind over with . see it it gets a blue spark.

i just brought a new coil from ebay. bike been sitting for few years know.

first thing it laks oil seems bit strange comment does he mean burns oil etc ring or cylinder wear in the cylinders.

if so i think it be trashed . or does it leak that much on the garage floor ? unlikey.

first thing if was my bike change to oil and filter but before that as its no point if the cyclinder head gasket gone.

is check the radiator water colour . in the mean time i strat it up and sqwezze all the hoses from rad to the engine.

might be air if it been changed . id whould check the air box make sure filter is there.

personlly if was me i drain the radiator completly if there was just water no anti frezze poor maintence i suspect.

even if you just add clean water and no anti frezze it be better than the shit that be in there .

know check the old coolent for any oil residue you know it l seen it before its have brown tint and be floating with the water.

the bike should not be doint whats its doing and you damage it if you keep running it .

the idle might be crap in the carbs . or the charging sytem battery statror .

you local library might have a manuall i have one for the us vt 500 ascot and it covers the vt 500 e as well.

i d love to help you let me know . i got sort mine as i go belive me my bike in far worse shape . hacked wiring no key or fuse box

missing . its a soldi bike so it worth having a go . but dont spend money on it till you know how the engine is.

your just pour money down the drain.

check your spark plugs i clean them with wire brush (i know say not to then blow any crap out)

i add a picture of my bike that should make yours look a millon dollars ;-)

remember the basic,s spark compression air/fuel step by step check things keep it simple get some good info

your be right . there is a vt 500 facebook page so imagine there be a nv one. same engine just smaller

[actungbaby]

David Silver Spares www.davidsilverspares.co.uk

www.cmsnl.com

www.econohonda.co.nz


are my three go-to sites for old Honda parts. Try local first obviously - they have a very good range of stuff.

good luck with it.

best bet ebay cheaper esp for the coils gaskets yes the above plugs i get at a dealer. they can look up the right plugs.

[actungbaby]

Unlikely as they are in the same family of Engine codes. but nothing is imposible if honda figured it would save them some money.
From what i understand the bros and the NVT650 revere share the same mounts only the engine direction is reversed because of the shaft drive.
On those engines the shaft can be converted to chain drive with Bros/Hawk parts output shaft etc. but it will still run in the wrong direction.

peter sales has a honda bros 650 ccc engine on trademe .600.00 no carbs though.

[husaberg]

peter sales has a honda bros 650 ccc engine on trademe .600.00 no carbs though.

I am 100% sure they wouldn't fit without a heck of a lot of mods. the bros/ntv650 was an example sorry for any confusion.